Drilling tool structure As shown in Fig. 5.2, the Dth hammer coring tool belongs to the structural type of double-acting double-tube coring tool; it is mainly composed of upper joint 1,fastest dth hammer, anti-torque washers 2 and 8, O-rings 3 and 11, pin 4, inner tube joint 5, outer tube 6, inner tube 7, The average slope of the middle part is 31 °, and the rear part is a gentle slope section with a slope of about 10 °. According to the deformation development process, genetic mechanism and sliding characteristics of the landslide mass, the landslide area is divided into three areas: the main sliding area (including two subareas I-1 and I-2), the left rear traction area (II) and the right rear traction area (III) (Fig. 5.5 and Fig. 5.6). Figure 5.5 Landslide behind Jianshe Street, Danba, Sichuan Fig. 5.6 Plan of Landslide behind Jianshe Street in Danba, Sichuan According to the geological environmental conditions of the landslide, on the basis of the measured 1:500 topographic map, the comprehensive exploration was carried out by using the technical methods of engineering geological mapping, geophysical exploration, drilling, trenching, field and indoor tests, and landslide dynamic monitoring. The application of each exploration technology and method is as follows. (1) Engineering geological mapping The engineering geological mapping of the landslide area and a certain range of peripheral slope sections has been carried out, covering an area of 0.342 km 2. Through engineering geological surveying and mapping, the external shape, elements and deformation characteristics of the landslide are identified, which provides the basis for geophysical exploration, drilling and trenching, and monitoring. (2) Geophysical prospecting According to the characteristics of the accumulation layer landslide of Jianshe Street landslide, the high and steep terrain, and the difficulty of heavy exploration work such as drilling and mountain engineering, the application of geophysical exploration methods is strengthened in exploration technology and methods. High-density electrical method and electrical sounding method are used in geophysical prospecting. 15 (scale 1:500) geophysical profiles totaling 4.9 km and 3 (scale 1:200) geophysical profiles totaling 3.5 km are arranged, and 970 high-density electrical survey points and 18 electrical sounding survey points are set. Wenner device is selected for high-density electrical method, and the electrode spacing is 5m. The number of electrodes is 60 and the supply voltage is 180 V. Symmetrical quadrupole device is used for electrical sounding, the minimum AB/2 is 1.4m, the maximum is 115m, MN/2 is 1m, and the power supply voltage is 180V. Through geophysical prospecting, drilling and engineering geological mapping, the thickness of the sliding mass in the landslide area and the undulation and burial depth of the underlying bedrock are basically ascertained. (3) Drilling According to the armchair landform characteristics of the landslide and the distribution of cracks, one longitudinal main exploration line and two auxiliary exploration lines are arranged along the main sliding direction, and one main exploration line and two auxiliary exploration lines are arranged horizontally. Seven boreholes are arranged at the intersection of the exploration line, with a total footage of 318 m and an average hole depth of 45 m. In the later stage, 7 supplementary exploration boreholes were arranged according to the needs of the treatment project. The main exploration profile is shown in Figure 5.7. Fig. 5.7 Longitudinal Section of Landslide at the Back of Jianshe Street in Danba, Sichuan Full-hole coring is adopted for drilling, and vegetable glue hole protection or casing drilling technology is adopted for the overburden, so that the core recovery rate of the landslide body reaches more than 80%. The drilling identified the thickness of the landslide, the location and shape of the sliding surface, the depth of groundwater and the nature of the underlying rock and soil mass of the sliding surface, which provided basic geological data for the calculation of landslide stability and the judgment of its development trend. (4) Mountain engineering Trenching was used in mountain engineering, and four trenches were set at the cracks at the rear edge of the landslide to understand the contact relationship between different rock and soil masses and the tensile cracks, and sampling tests were carried out. (5) Field and indoor tests Soil sample: the landslide mass is mainly composed of block stone and soil, and it is difficult to obtain the soil sample, so only one group of soil sample is taken from ZK4 borehole for indoor routine test. In combination with the trench excavation work at different locations on the sliding mass, 6 groups of heavy gravity tests were completed. Rock samples: 8 groups of samples were taken from each borehole for laboratory tests, and the physical and mechanical data of rocks were obtained for the design of landslide control. (6) Landslide dynamic monitoring In order to fully grasp the landslide deformation activities, since January 21, 2005, 46 professional monitoring points (total station monitoring) and 26 simple artificial monitoring points have been gradually set up on the landslide mass according to the landslide activity conditions, and special personnel have been assigned to conduct manual inspection on various deformation and failure signs of the slope mass. At the same time, three deep displacement monitoring holes are arranged on the main exploration line of the landslide,Borehole Drill Bits, and the deep displacement of the landslide is monitored in real time by the borehole inclinometer. Abundant surface and deep displacement monitoring information provides an important basis for landslide stability analysis and information design and construction of control engineering. This article is selected from Technical Guidelines for Landslide Prevention and Control (Yin Yueping et al., Geological Publishing House, 2018). Return to Sohu to see more Responsible Editor:. wt-dthtools.com
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