钻孔联合地质剖面探测施工中若干问题探讨

Discussion on several problems in the construction of joint drilling geological section surveys

基于《活动断层探测》GB/T 36072—2018、《活动断层探查钻探》DB/T 92—2022等现行规范规程,对跨隐伏活动断层的钻孔联合地质剖面探测施工的基本要求和存在的主要问题进行了探讨,认为现行技术标准存在的问题有:(1)对岩芯采取率的要求偏低;(2)对横跨隐伏逆断层的钻孔深度和钻孔之间距离的要求偏低.提出了下列改进措施:(1)各类岩土的岩芯采取率应大于现行技术标准要求的数值;其中,黏土的岩芯采取率应不小于99%;(2)对横跨隐伏逆断层的钻孔深度应大于现行技术标准要求的孔深;在第四系厚度较薄时,在逆断层上断点附近,位于逆断层上盘的钻孔在钻遇上盘的前第四系后,还应继续钻进,钻孔深度应达到能够揭露逆断层下盘的前第四系的深度;(3)当隐伏逆断层在第四系中的断距较小时,逆断层上断点两侧的2个相邻钻孔间距就需要1~3 m甚至更小的数值.补充了钻孔联合地质剖面探测中的钻孔布设方式、隐伏断层产状的求取方法.分析了在钻孔联合地质剖面探测的断层识别中存在的一些不确定性因素,并提出了相应对策.指出钻孔联合地质剖面探测施工是基于动态设计的信息化施工,现场技术负责人及其施工现场技术管理在钻孔联合地质剖面探测工作中起着重要作用.

Based on"Surveying and prospecting of active fault GB/T36072-2018","Active fault survey—drilling DB/T 92-2022"and other current standards,the basic requirements and main problems in the construction of joint drilling geological section surveys across hidden active faults are discussed.The current technical standard has the following problems:(1)the requirement of core recovery rate is low;and(2)low requirements for drilling depth and distance between boreholes across the hidden reverse fault.The following improvement measures are put forward:(1)the core recovery rate of all kinds of rock and soil should be greater than the value required by the current technical standards and the core recovery rate of clay should not be less than 99%;(2)the drilling across the hidden reverse fault should be deeper than the depth required by the current technical standards;when the thickness of the Quaternary system is thin,the drilling located in the hanging wall of the reverse fault near the uppermost point should continue to drill after drilling into the pre-Quaternary system in the hanging wall,and the drilling should reach the depth that can expose the pre-Quaternary system in the footwall;(3)when the fault displacement of the hidden reverse fault in the Quaternary system is small,the distance between the two adjacent boreholes on both sides of the uppermost point of the reverse fault needs to be 1-3 m or even smaller.The drilling layout method and the method of determining the occurrence of hidden faults in the joint drilling geological section surveys are added.Some uncertain factors in fault identification of joint drilling geological section surveys are analyzed,and corresponding countermeasures are proposed.It is also pointed out that the construction of joint drilling geological section survey is an information construction based on dynamic design,and the on-site technical director and their construction site technical management play an important role in the joint drilling geological section surveys.