Recently，Learned from Wuhan Zhengyu Kechuang Geotechnical Engineering Co., Ltd.，It was builtWuhanAfter the excavation of the radio and television all-media center project site,，The effect of waterproof curtain is highly recognized by the owner.，SMCThe construction method has also been praised again.，Shanghai JintaiSMCThe drilling rig of the construction method has once again taken the lead in the landmark buildings.。
According to the pumping interconnection test report of the project,：When the water level in the pit drops to the elevation required by the design and construction，Pumping capacity in the pit 242m³/h，Based on regional experience，SMCThe water-stop effect of the water-stop curtain at the bottom is better。
The result of this experiment is no matter for Shanghai Jintai or Zhengyu Kechuang.，It's all good and exciting news.。
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Project overview——Radio and Television All-Media Center Project
Project overview
Wuhan Radio and Television All-Media Center ProjectThe foundation pit is adjacent to Wuhan Rail Transit No.2、Line 3 with large excavation depth，The construction party and the Metro Group attach great importance to it.，Zhengyu KechuangSMCConstruction unit of construction method，Treat the project as an annual key project of the company。
So far，The excavation of the first basement of the foundation pit has been successfully completed.，Groundwater is well controlled throughout the excavation process.，Adjacent Wuhan Rail Transit No.2、Monitoring data of Line 3 and surrounding areas，Cumulative settlement、The change rate is within the alarm value range.，No abnormal conditions。
Current situation of foundation pit excavation
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The excavation area of Wuhan Radio and Television All-Media Center Project is about 25000m²，Ordinary excavation depth 18.55m，The deepest part of the pit in the pit is dug to a depth of 20.55m，AdoptSMCFalling water-stop curtain，The depth of the wall is designed to be 1m into the highly weathered rock stratum.，Effective wall length 43.0~45.0 meters。
Schematic Diagram of Relationship between Foundation Pit and Subway
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Wuhan Zhengyu Kechuang Geotechnical Engineering Co., Ltd. focuses on the construction and method promotion of ultra-deep cement-soil waterproof curtain，It is one of the strategic partners of Shanghai Jintai Construction Machinery Co., Ltd.，It is also Shanghai Jintai.SMCFirm practitioner and supporter of construction technology and equipment！Review the trial wall stage of the project，Zhengyu Kechuang has held several internal seminars with Shanghai Jintai.，A detailed and feasible trial wall construction scheme is worked out.，Implement strictly according to the plan，Construction of 3 trial walls（Different combinations of parameters），The results of the core pulling test after 14 days of wall formation show that，Wall integrity、Both the strength and the depth into the rock meet the design requirements.，Obtain the approval of all parties involved in the project，Successfully enter the formal construction stage。
Site Construction Drawing of Radio and Television All-Media Center Project
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Wall integrity is the most important part of the quality control of cement-soil mixing wall，Shanghai Jintai and Zhengyu Kechuang，It has been constantly exploring and innovating on the issue of wall integrity.，Invest more than one million yuan，Continuously improve the tool、Try a variety of drilling, mixing, and guniting methods.，Stick to the details，Try various tripping and lifting speeds.、Gunite parameters、Combination of milling wheel rotation direction and speed, etc.，And carry out core-pulling comparison one by one.，Accumulated rich experience，Have a clear idea of which combination of parameters should be used for which geological conditions，Finally, the project of Radio and Television All-Media Center blossoms and bears fruit.，The third-party core-pulling test results show that the quality of the wall is excellent.。
Legend of core sample tested by the third party
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Before formal excavation of foundation pit，Wuhan Survey and Design Co., Ltd. has carried out pumping connection test.，Through field pumping test and recovery test，Observe and master the water level variation characteristics of deep confined water caused by pumping.，The main objectives are as follows:：
（1）Judge whether the closure and dewatering effect of the waterproof curtain can meet the design requirements；
（2）Qualitative analysis to judge the water sealing effect of falling curtain。Predict the ground subsidence and evaluate the impact on the surrounding environment after foundation pit dewatering；
（3）Check the drainage capacity of the drainage system around the foundation pit；
（4）By connected pumping test，Guide the secondary deepening design of the project precipitation；
（5）Accumulate through multiple projects，Obtain the hydraulic connection and seepage law inside and outside the pit under the condition of falling waterproof curtain。
After more than a month of rigorous testing,，The report issued by Wuhan Survey and Design Co., Ltd. draws the following conclusions.：
（1）The area of foundation pit is about 25000㎡，Through the opening of the dewatering well，The water level in the pit can be stabilized at the absolute elevation：0.5～1.9m，Total pumping capacity in the pit 241.9m³/h，It is equivalent to the water output of four pumps of 60 cubic meters.；
（2）The maximum drawdown of water level in the observation well outside the pit is 1.75-3.17mBetween；
（3）Based on regional experience，SMCThe water-stop effect of the water-stop curtain at the bottom is better，The foundation pit has the conditions for continued excavation。
Water level curve summary diagram inside and outside the pit
Curve Summary of Water Level Inside and Outside the Pit Broken Line Chart of Water Yield of the Foundation Pit Every Half Hour
Supplementary experiment—General diagram of water level trend of adjacent observation wells inside and outside the pit
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Overall evaluation
Overall evaluation
The test report of pumping connection inside and outside the pit prepared by Wuhan Survey and Design Co., Ltd. is comprehensive.，The monitoring data are basically credible.，After improvement, it can guide the follow-up work.。
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Comments and suggestions
Comments and suggestions
The test results show that，When the water level in the pit drops to the elevation required by the design and construction，Pumping capacity in the pit 242m³/h，Based on regional experience，SMC The water-stop effect of the water-stop curtain at the bottom is better，After improvement according to the following opinions，The foundation pit has the conditions for continued excavation。
The results of the pumping connection test have been unanimously approved by experts and the Metro Group.，At present, the foundation pit is being excavated in an orderly manner.，Drawing a successful conclusion for 2022.，It also foreshadows a higher level in 2023.！
ThanksWuhan Zhengyu Kechuang Geotechnical Engineering Co., Ltd.Provide valuable case materials
