Comparison of pump suction reverse circulation and gas lift reverse circulation technology
1 Construction process
1.1 The pier for the drilling platform is located on the side slope of the embankment on the west side of the Beijing-Hangzhou Canal, with the lowest elevation of 7.6 m, the highest elevation of 12.11 m, the elevation of the pile top of pier 13 + 1.806 m, the elevation of the bottom of the pile:-78.194 m, the pile length is 80 m. Excavate the high part of the river embankment and lower it, fill the excavated earth to the low-lying part of the slope, use an excavator (excavator simulation) to roll layer by layer, and drive steel sheet piles on the water side to retain the soil to form a borehole Platform, the platform elevation is 9.0 m. Two HY 500 drilling rigs are put into the No. 13 main pier. The plane of the drilling platform is leveled with a level. In the drilling construction, check the levelness of the drilling rig platform with a flat rule at any time, and if the platform is found to be uneven, operate the pad in time.
1.2 Making and burying of protective tube 1) Making of steel protective tube. The steel protective tube is made of A3 steel plate, the wall thickness is 14 mm, and the inner diameter is 2.80 m. A total of 12 are made, and there are 6 piers 13 and 14 each, which are used in rotation. The design length of the steel protective tube is 6 m, and it is made in 2 sections, the upper section is 1 m, the lower section is 5 m, and the 1.0 m section can be used in circulation. The protective cylinder is made in the factory, and the joints of the steel plates are welded by slit welding, and the quality of the welds is checked by kerosene coating. The roundness, flatness of the end face and the parallelism of the flange are strictly controlled during production. Buried steel protective tube. According to the distribution of soil quality, the buried depth of the protective tube is determined to be 5 m. During construction, the actual buried depth of the steel protective tube is adjusted according to the specific conditions. In principle, the buried depth of the steel protective tube must pass through the soft soil layer and sink The clay layer is 1.0 m 1.5 m. The buried steel casing is about 1.0 m above the ground and about 1.5 m above the water level of the canal during the construction period.
1.3 Mud circulation system and mud preparation adjustment The mud pool is arranged on the south side of the drilling platform on the west bank of the canal. The original ground is leveled and compacted. The mud pool wall is masonry with red bricks, plastered with mortar, and the bottom of the pool is paved with gravel and poured. 6 cm thick concrete with a volume of 450 m3. The mud tank is divided into 3 tanks, namely, slurry tank, slurry tank, and sedimentation tank. The partition walls of each tank are connected by gaps, and the top of the slurry tank is higher than the mouth of the protective cylinder to form a reverse circulation. Due to the high drilling platform, the mud tank is arranged on the ground by trenching, and the bottom and side walls of the trench are stacked with soil bags, and the top is covered with colored strips. Both ends of the mud tank and the mud pool, no fracture zone, landslide, underground river and karst development zone.
2 Conclusion
Compared with other survey methods, the high-density electrical method has the following advantages:
1) High degree of automation. With a one-time arrangement, it can complete the whole process of automatic pole running, automatic observation, automatic recording, automatic calculation, automatic mapping and imaging of various detection devices;
2) Reduced human error. Eliminate errors in point location, observation, recording, calculation, drawing, etc., greatly improving the accuracy of survey results;
3) Improve the efficiency of engineering survey work and reduce labor intensity;
4) The imaging technology makes the survey results intuitive and makes it easy for geotechnical personnel to interpret and use the survey results;
5) In areas with favorable terrain and physical conditions, the high-density resistivity method can truly and intuitively reflect engineering geology, hydrogeology and other issues, and can quickly, scientifically and reasonably evaluate the site.
