Abstract:The project team of China Geological Survey “Land Trial Production of Natural Gas Hydrate in Sea Area” has constructed a drilling test site in the coastal beach area of Dongying City, Shandong Province. The foundation soil of the site is typical silty clay in the Yellow River Delta, which has the characteristics of micro-vibration liquefaction. By comparing the advantages of cost, construction period, environmental protection and applicability, the project team chose the construction scheme of lime-soil cushion and strictly controlled the construction quality. Lime-soil cushion can form effective water-proof layer, isolate groundwater rising channels and surface water seepage channels, avoid the causes of micro-vibration liquefaction, and eliminate the seepage of construction waste water in the site. At the same time, static compaction was used throughout the backfilling construction to avoid the upward migration of pore water and micro-vibration liquefaction effect of soil. The backfilling area is divided into heavy-load area and light-load area. Different backfilling schemes were adopted, which not only met the bearing capacity requirements, but also saved costs. The backfilling schemes have achieved good construction results, ensuring the smooth operation of the test site.

Abstract:Taking a project in Dongying as an example, based on the test results of pile test in the Yellow River flood alluvial formation, the relation curve between the measured average value of the ultimate bearing capacity of single pile and the height of the pile bottom (which can be converted into pile length) under the condition of the same pile top elevation (-5.7m) is set up. The difference between the test pile test and the measured value of the ultimate bearing capacity of the single pile is quite different from the predicted value. The reasons and the optimal design method of pile foundation bearing capacity are introduced. According to the test results of the pile foundation, the measured value of the ultimate bearing capacity of the single pile under the same length and diameter of the pile is about 10% compared with the predicted bearing capacity, which can achieve the potential of excavating the geological conditions, reducing the number of piles and saving the cost of the project. Relevant test methods and methods of optimizing pile bearing capacity design can provide reference for engineering design under similar geological conditions and the establishment of regional pile bearing capacity database.

Abstract:Zhongning County is located in the middle Yellow River. Yellow River beach groundwater is supplied by Yellow River, which has great potential for mining water. For the riverside well field in the Quaternary clay sand gravel stratum of Zhongning Yellow River beach， radial well was selected to be water conservancy building and 5 wells were completed. The collecting well was constructed with reverse circulation method and special bit was equipped to fish the boulders in aquifer with particle size more than 200mm, the horizontal radiation tube was constructed by full hydraulic horizontal drilling rig with torque, thrust force, pulling force and vibro-compaction. The “equivalent big diameter well” was used to calculate pumping capacity of radial well. The data of pumping test and related information were analyzed to compare the stable water yield and drawdown of radial well, tubular well and large diameter well, the results show that the radial well is an effective way for the exploitation in the similar water resources.

Abstract:Combining the production and scientific research, 8 water wells were constructed with normal circulation drilling method and 11 water wells were constructed with pump suction reverse circulation drilling method in groundwater resource region along the Yellow River in Zhengzhou. By the analysis on the efficiency and economy of these 2 different drilling technologies, the conclusions were got: in groundwater resource region along the Yellow River in Zhengzhou, the best well depth should be smaller and larger than 140.75m respectively with pump suction reverse circulation drilling method and with normal reverse circulation drilling method each. The conclusions can be the reference for water well construction in the similar area.