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Delivery: <= 6 days. True-PDF full-copy in English will be manually translated and delivered via email. DBT81-2020: Active fault survey - Paleoseismic trenching Status: Valid
Basic dataStandard ID: DB/T 81-2020 (DB/T81-2020)Description (Translated English): Active fault survey - Paleoseismic trenching Sector / Industry: Chinese Industry Standard (Recommended) Classification of Chinese Standard: P15 Classification of International Standard: 91.120.25 Word Count Estimation: 36,347 Date of Issue: 2020 Date of Implementation: 2020-07-01 Issuing agency(ies): China Earthquake Administration DBT81-2020: Active fault survey - Paleoseismic trenching---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.(Exploration of active faults) ICS 91.120.25P15 People's Republic of China Earthquake Industry Standard Active fault exploration ancient seismic trough exploration Released on 2020-03-30 Implementation of 2020-07-01 Issued by China Earthquake Administration Table of contentsPreface Ⅲ Introduction Ⅳ 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Work process 2 5 Preliminary preparation 4 6 Location selection 4 7 Topographic mapping and trench excavation 5 8 Preparation of the groove record 6 9 Interpretation of exploration trenches and paleoearthquake identification 6 10 Sampling and dating 7 11.Ancient earthquake identification mark 9 12 Outcomes 10 Appendix A (informative appendix) Example of trough location 11 Appendix B (Informative Appendix) Trench Excavation and Record 16 Appendix C (Normative Appendix) Test Method for Analysis Results of Ancient Earthquake Events 19 Appendix D (Normative Appendix) Limiting methods for determining the age of ancient earthquake events 22 Appendix E (informative appendix) Paleoearthquake recognition model and example results 24 References 31ForewordThis standard is one of the series of standards for "Active Fault Exploration". The standard structure and name of the series are expected to be as follows. ---Remote sensing survey for active fault detection (DB/T 69-2017); --- Active fault exploration field geological survey (DB/T 82-2020); --- Active fault exploration and fault geomorphological survey (DB/T 71-2018); ---Active fault exploration, ancient seismic trench exploration (DB/T 81-2020); ---Active fault exploration and drilling; ---Dating test of active fault exploration; ---Active fault exploration and seismic exploration; ---Activity identification of active fault exploration; ---Evaluation of seismic hazard of active fault exploration; ---Graphic symbols for active fault exploration (DB/T 72-2018); ---Active fault exploration database; ---Active fault exploration database detection (DB/T 83-2020); ---Active fault exploration 1.25,000 seismic structure map compilation (DB/T 73-2018); ---Report on the results of active fault exploration; --- 1.5000 active fault mapping (DB/T 53-2013); --- 1.5000 active fault mapping database specification (DB/T 65-2016); This standard was drafted in accordance with the rules given in GB/T 1.1-2009 "Guidelines for Standardization Work Part 1.Standard Structure and Compilation". This standard was proposed by the China Earthquake Administration. This standard is under the jurisdiction of the Earthquake Disaster Prevention Standardization Technical Committee. Drafting organizations of this standard. Institute of Geology, China Earthquake Administration, Institute of Crustal Stress, China Earthquake Disaster Prevention Center, Institute of Earthquake Prediction, China Earthquake Administration, Seismological Bureau of Ningxia Hui Autonomous Region. The main drafters of this standard. Ran Yongkang, Xu Xiwei, Wang Hu, Chai Chizhang, Yu Guihua, Yang Xiaoping, He Honglin, Leng Wei, Wu Xiyan, Liu Huaguo, Gao Shuaibo. National Earthquake Disaster Prevention Center; Zip Code. 100029), and indicate the contact information.IntroductionNumerous site surveys of major earthquakes at home and abroad and analysis of their disaster phenomena show that active faults are the source of earthquakes and also earthquake disasters. The culprit. Finding out the exact location of seismically active faults and making scientific evaluations of their attributes and seismic risk is an earthquake disaster risk assessment And the important basic work of earthquake disaster prevention. Since the "Eighth Five-Year Plan" period, my country has gradually promoted the detection of active faults. Great progress has been made in urban planning, land use, and engineering construction. Some practical experience has been accumulated. And earthquake science research and other fields have played an important role. In recent years, the seismic department has organized and carried out active fault detection technology to sort out the work process, work content and work results. This framework. In order to standardize and guide our country’s active fault detection work and its application, the GB/T 3602-2018 "Active Fault Layer detection", the standard provides technical requirements for active fault detection in terms of work content, workflow, technical methods, data management, and outcome output. The requirements are stipulated. On this basis, further evaluation and analysis of various technical methods to achieve detection purposes are carried out to clarify their technical indicators and Data collection requirements and a standard framework for active fault detection have been constructed. Paleoseismic trench exploration is one of the main technical methods for active fault detection and location, fault activity identification and seismic risk assessment. It has been widely used in active fault detection, active fault mapping, and active fault investigation on engineering sites. In view of the identification of trenches and ancient earthquakes Complexity, it is necessary to standardize trenching technology and ancient seismic identification methods, and this standard is specially formulated. Active fault exploration ancient seismic trough exploration1 scopeThis standard specifies the preliminary preparation, site selection, site excavation, sample collection, identification of paleo-seismic events and related cost Requirements for data storage. This standard applies to geological mapping of active faults, urban active fault detection, and paleo-seismic trough exploration in active fault identification. Ground Earthquake scientific investigation can also be used as a reference.2 Normative referencesThe following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated references, the latest version (including all amendments) applies to this document. GB/T 15608-2006 China Color System DB/T 65-2016 1.5000 active fault mapping database specification DB/T 69-2017 Active Fault Exploration Remote Sensing Survey DB/T 71-2018 active fault exploration fault geomorphological survey3 Terms and definitionsThe following terms and definitions apply to this document. 3.1 There have been active faults since 120,000 years ago, including Late Pleistocene faults and Holocene faults. [GB/T 3602-2018, definition 3.1] 3.2 There have been faults, but it is difficult to identify the faults of the dislocation plane in the formation. 3.3 The amount of slip generated by an active fault during an earthquake rupture. [GB/T 3602-2018, definition 3.13] 3.4 There are no written records of earthquake events discovered by geological methods. [GB/T 3602-2018, definition 3.16] 3.5 A valley developed along the fault line.4 Work process4.1 Figure 1 shows the ancient seismic trough exploration workflow, including the following 7 stages. a) Preliminary preparation; b) Location selection; c) Topographic mapping and trench excavation; d) Preparation of groove record; e) Exploration trench interpretation and paleo-seismic identification; f) Sampling and dating; g) Results and outputs. 4.2 Trench interpretation, sampling and dating, and paleoearthquake identification can be carried out simultaneously.5 Preparation5.1 Data collection 5.1.1 High-resolution remote sensing images of target faults, research on the activity of existing faults, and results of trench exploration work should be collected. 5.1.2 The stratum, structure, topography and climate data along the active fault at pre-selected locations and nearby areas should be collected and sorted out. 5.2 Image interpretation 5.2.1 Remote sensing images with a resolution better than 1m shall be used to determine suitable locations for trenching work, and shall be processed in accordance with the provisions of DB/T 69-2017 Line image interpretation. 5.2.2 For strike-slip faults, fault troughs, fault plug ponds, fault depression ponds, small pull-off basins, small gullies and gully beds, etc. shall be identified Location. 5.2.3 For normal faults and reverse faults, the stratified landforms of the ascending disk of the fault and the fault ridges, and the graben and depressions in front of the fault ridges shall be identified. To wait. 5.3 Field survey 5.3.1 Field surveys should be carried out on pre-selected locations to assess whether they meet the requirements of Chapter 6. 5.3.2 The geomorphology of the preselected site should not be artificially modified, and the impact of artificial modification should be assessed if it cannot be avoided. 5.3.3 The coseismic displacement of ancient earthquake events should be evaluated based on the interpretation results of remote sensing. 5.3.4 The structural position of the preselected location of the exploration trench along the target fault shall be evaluated. 5.4 Data storage It shall be in accordance with Table A in DB/T 65-2016.1.Table A. 4 ~ Table A. 13.Table A. 25.Table A. 28 ~ Table A. 31 requirements are collected The data information is merged into the database.6 Location selection6.1 Basic requirements 6.1.1 The location should be selected where the fault structure is simple, the accumulation is continuous, and the accumulation is clearly layered, and the dating samples can be collected. 6.1.2 The location of the exploration trough should be avoided. a) Fault trough developed by soluble rock and seismic depression; b) The slope of the trough is steep, and the part where coarse particulate matter accumulates at the foot of the slope; c) Locations with frequent erosion and accumulation; d) Areas affected by landslides and debris flows; e) Areas with abnormal development of freezing and thawing. 6.2 Location of strike-slip fault trench 6.2.1 Pull-apart basins, fault troughs, fault plug ponds, fault depression ponds, gully beds staggered by faults, etc. should be selected, and meet the following requirements. a) Pull-apart basins with a width of less than 100m are preferred. For large pull-apart basins, the oblique cut-off layer in the basin is preferred. Select the boundary fault location; b) Select a fault trough with a width of less than 150m, and select a low-lying or relatively convergent place in the trough; c) Choosing faulty ponds and rifting ponds with a width less than 100m; d) Select the part where the gully passes through the fault at a near vertical or large angle, and both sides are young accumulation strata; e) The width of small gullies staggered by faults should be less than 5m. 6.2.2 Figure A in Appendix A. 1~Figure A. 4 gives four examples of location selection for strike-slip trenches. 6.3 Location of reverse fault exploration trench 6.3.1 It is advisable to choose a site with a single steep ridge, continuous accumulation in front of the ridge, and a cumulative height 2 times or more than the coseismic displacement. Choose alluvial fans, Fault ridges on the second or third terraces of rivers, reverse ridges or depressions caused by thrusting. 6.3.2 Figure A. 5 gives an example of location selection for reverse fault trenches. 6.4 Location of normal fault trench 6.4.1 It is advisable to choose a site with a single steep ridge, continuous accumulation in front of the ridge, and a cumulative height 2 times or more than the coseismic displacement. Choose alluvial fans, The steep ridge of the fault on the second or third terrace of the river, the part with a small graben structure. 6.4.2 Figure A. 6 gives an example of location selection for normal fault trenches. 6.5 Data storage After the site selection is determined, it should be in accordance with Table A in DB/T 65-2016.The 40 requirements fill in the location coordinates and store them in the warehouse.7 Topographic mapping and trench excavation7.1 Basic requirements 7.1.1 The trench layout and excavation style should be selected according to the nature of the fault and the excavation target, and the scale of excavation should be determined. Figure B in Appendix B. 1 An example of trench excavation style is given. 7.1.2 It is advisable to take photos to record the original topography of the excavation site. 7.1.3 During the construction of the trench, when the depth of the trench is greater than 2m, supporting measures should be taken to prevent the trench from collapsing. 7.1.4 When excavating a trench with a depth greater than 3.5m, the stepped excavation method should be adopted, the step width should be 1m, and the step height difference should be 1.7m~ 2.3m. 7.2 Topographic surveying and mapping 7.2.1 Before excavation of the trench, it is advisable to carry out the faulty geomorphological survey near the location of the trench in accordance with the regulations of DB/T 71-2018. 7.2.2 The range of topographic surveying and mapping shall cover the exploration trench and nearby structural deformation geomorphology. 7.3 Excavation of trench 7.3.1 Strike-slip fault 7.3.1.1 It is advisable to first excavate a trench that spans the entire fault zone, and then, according to the exposed fault position, be perpendicular or parallel to the excavation combination of the fault. Probe groove. Figure B in Appendix B. 2 gives an example of plan layout and excavation of strike-slip fault trench. 7.3.1.2 The stratum and structural information can be exposed by stripping the trench wall layer by layer. 7.3.1.3 Where there are no conditions for excavation of combined trenches, two or more vertical fault trenches should be laid. 7.3.1.4 The depth of the trench should not be less than 2.5m, and the width of the bottom of the trench should be greater than 1.5m. 7.3.2 Reverse fault 7.3.2.1 A vertical fault should be laid and a trench that spans the entire surface rupture zone of the Late Quaternary, and a location with a complex topography or accumulation pattern in front of the ridge It is advisable to lay a combined trough. Figure B. 3 gives an example of the plane layout and excavation of a reverse fault trench. 7.3.2.2 The depth of the trench should be more than twice the co-seismic displacement, and the bottom width of the trench should be greater than 1.5m. 7.3.2.3 Excavation of the ascending disk should be able to control the surface rupture zone of the Late Quaternary, the length should account for 3/5 of the length of the entire trench, and the descending disk should be fully exposed Accumulation of slope belt in front of ridge. 7.3.3 Normal fault 7.3.3.1 A vertical fault should be laid out and a trench that spans the entire Late Quaternary surface rupture zone, where there are graben and other complex structures in front of the ridge can be deployed Set up a combined probe. Figure B. 4 gives an example of the layout and excavation of a normal fault trench. 7.3.3.2 The depth of the trench should be more than twice the co-seismic displacement, and the bottom width of the trench should be greater than 1.5m. 7.3.3.3 The excavation length of the descending plate should account for 2/3 of the entire length of the trench. 7.4 Data storage It shall be in accordance with Table A in DB/T 65-2016.40.Table A. 45 ~ Table A. The requirement of 50 summarizes the topographic surveying and mapping data of the excavation point and the trench gauge The mold parameters are merged into the library.8 Preparation of groove record8.1 Trough trimming The trough should be repaired and meet the following requirements. a) Clean the walls of the trench first to ensure that it is level and free of floating soil coverage, and the stratum boundaries and structural signs are clear; b) The sand layer should be leveled, and excavation scratches and other artificial marks should be removed; c) The gravel layer should be basically flat. 8.2 Trench mark Different color labels should be used to mark on the wall of the trough. The information to be marked includes. a) Signs of fault activity such as fault traces, stratum deformation and structural wedge; b) Special sedimentary strata such as marker strata, buried soil, collapse wedge and filling wedge; c) Sample location, fossils or special deposits, such as animal hair, volcanic ash, baking layer, mineral nodules or rich accumulation layer and other dating materials Location. 8.3 Network building imaging 8.3.1 A 1m×1m reference grid coordinate should be established. 8.3.2 The orthographic image of the trench wall shall be made in one of the following ways. a) Take photos with grid as the unit, and the overlapping area of adjacent photos is not less than 20%; the optical axis of the camera should be perpendicular to the surface of the groove, and the light should be selected. Take pictures when the line is stable and soft; do ortho-correction and stitching of the photos to make an orthographic image of the trench wall; b) Use other technical methods to obtain orthographic images of the trench wall. 9 Interpretation of exploration trenches and paleo-seismic identification 9.1 Preliminary interpretation 9.1.1 Faults should be marked on the trench wall. 9.1.2 According to sedimentary unconformities, changes in the accumulation environment, such as grain size, color mutation and other phenomena, preliminary division and identification of stratigraphic units, piles Accumulate the order, and analyze the causes of each level unit. 9.1.3 The ancient earthquakes shall be identified, marked and described in accordance with the provisions of Chapter 11. 9.2 Probe record 9.2.1 The stratigraphic unit should be outlined on the orthophoto of the trench wall, and information such as genetic type, structural deformation and paleo-seismic event layer, samples and fossils, and special deposits should be marked to form an interpretation map of the trench profile. Figure B. 5 gives an example of a groove record. 9.2.2 The trough information shall be described in accordance with the following requirements. a) Describe the stratum color in accordance with the color code of the color system specified in GB/T 15608-2006; b) Use gravel, coarse sand-medium sand-fine sand-silt sand, clay-peat, bedrock-bedrock weathering, etc. to classify formation materials; c) Describe the roundness, sortability and particle size of gravel; d) Analyze the genetic types and bedding development of accumulative stratigraphic units; e) Describe the characteristics of the formation phase transition, collapse wedge and packing wedge accumulation; f) Describe whether there is local angular unconformity contact between the stratigraphic units; g) Describe whether there are fossils, mineral nodules or accumulations in the formation; h) Describe the paleosol layer and its degree of development; i) Describe the signs of deformation such as faults, joints, cracks, folds, and sand liquefaction. 9.2.3 The local directional characteristics of fine-grained materials and the local looseness of coarse-grained materials should be observed, or the directional sampling grinding piece should be used to test the hyperspectral and magnetic properties. Determine whether there is a hidden fault and its location based on the physical properties of the formation such as the rate of conversion. 9.3 Confirmation of ancient earthquake events 9.3.1 The interpretation map and written record information of the trough section sh......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of DBT81-2020_English be delivered?Answer: Upon your order, we will start to translate DBT81-2020_English as soon as possible, and keep you informed of the progress. The lead time is typically 4 ~ 6 working days. The lengthier the document the longer the lead time.Question 2: Can I share the purchased PDF of DBT81-2020_English with my colleagues?Answer: Yes. The purchased PDF of DBT81-2020_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. 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