Well point plastic draining pipe film coating type vacuum preloading and dewatering preloading combined power consolidation method

Abstract

The invention relates to a well point plastic draining pipe film coating type vacuum preloading and dewatering preloading combined power consolidation method. The method is characterized by comprising the following steps: levelling a site; determining to carry out or not carry out pre-tamping before dewatering; arranging a waterproof curtain; arranging an integrated well point plastic draining pipe vacuum system; coating the surface of a main pipe of the integrated well point plastic draining pipe vacuum system with a geotextile and a sealing film; then performing vacuum preloading, namely, constructing dams of cofferdams around the area to be reinforced, and pumping water from a water source in the periphery of the area to be reinforced into the cofferdams around the area to be reinforced, and then carrying out vacuum preloading, wherein underground water is completely pumped and returned to the surface of the area to be reinforced during the vacuum preloading; performing vacuum dewatering preloading, namely, forming openings in the constructed dams of the cofferdams to drain water stored in the dams of the cofferdams, and then carrying out vacuum dewatering preloading at a plurality of times, wherein full tamping is carried out after the last vacuum dewatering preloading; finally, vibrating and rolling in the whole site, then measuring the elevation, and handing over the completed project. The method has the advantages of being simple to operate, low in cost, and good in construction effect.

Description

technical field [0001] The invention relates to a method for treating weak ground, in particular to a dynamic consolidation method of vacuum preloading combined with dewatering preloading and film covering at well points. Background technique [0002] According to 7.1.1 of the "Code for Design of Building Foundations" (GB5007-2011), weak foundations refer to foundations mainly composed of silt, muddy soil, flushing soil, miscellaneous filling soil or other highly compressive soil layers. Before building construction on the weak foundation, it is necessary to consolidate the weak foundation first. The conventional consolidation treatment methods are as follows: [0003] 1. Conventional vacuum preloading reinforcement. Conventional vacuum preloading reinforcement "on land and under water in rivers, seas, lakes and swamps" soft soil foundations all need to be laid with sealing film and sand cushion, but there are the following disadvantages: [0004] 1. The construction of lar...

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Problems solved by technology

[0004] 1. The construction of large-area sealing membranes is difficult, and vacuum preloading on land requires a lot of manual laying of membranes with a low degree of mechanization, especially the construction of underwater vacuum preloading sealing membranes is more difficult;

[0005] 2. The PVC sealing film has low strength and is easy to damage and leak air. The cost of the second layer of sealing film and the first layer of geotextile is high, it is difficult to find the leak point, and the sealing effect is not good;

[0006] 3. A large number of PVC sealing films are not environmentally friendly;

[0007] 4. The surface under the film can reach a maximum negative pressure of 80kPa, and the negative pressure transmission loss to the deep part of the soil layer is fast. Generally, the loss of negative pressure per meter to the deep part is about 10kPa. The effective reinforcement depth is shallow;

[0008] 5. The loading surface is on the original ground surface or the backfilled land surface. Even if the surface sealing film does not leak, the slow air leakage of the shallow soil around the reinforcement area cannot be ignored, especially in the case of long-term loading for about 90 days, when the groundwater level drops to The degree of air leakage in shallow soil around a certain degree of reinforcement area is even more worrying

[0009] 2. The improved vacuum preloading reinforcement has the following disadvantages:

[0010] 1. The sand-removing cushion layer is changed to the mode of direct connection of plastic slabs with hand-shaped joints, and the mode of indirect negative pressure transmission is changed to direct negative pressure transmission mode, but it still needs a sealing film, and the maximum negative pressure loading surface is still on the surface;

[0011] 2. The sealing layer is formed by blowing and filling mud, or the vacuum branch pipe is directly connected to the plastic discharge into the soil for about 1.5 meters, or the vacuum filter tube is about 3 meters underground, and the side blister row replaces the sealing film. The dredging fill mud loses water, consolidates and cracks, the groundwater level drops rapidly, and the sealing effect is greatly reduced;

[0012] 3. The ultra-soft soil for land reclamation cannot be mechanically constructed. First, artificially insert the shallow layer of plastic drainage vacuum preloading, and then do deep vacuum preloading after the foundation strength is suitable for mechanical construction. The principle and process of conventional vacuum preloading are almost the same, only the simple difference between manual and mechanical, the process is more complicated, the cost is high, and the efficiency is low;

[0018] For traditional main pipes and branch pipes, submersible pump gravity dewatering is used for tube wells, and a combination of submersible pump gravity dewatering and vacuum dewatering is used for deep well dewatering. The spacing between well points is larger, generally 15*15m. The coarse and sparse treatment method focuses on precipitation. If the spacing is too large and the time is short, it cannot simultaneously have the effect of vacuum preloading and negative pressure consolidation;

[0019] Coarse and sparse distribution of genetic precipitation and short-term (about 30 days) treatment methods in the precipitation dynamic compaction treatment are only suitable for shallow treatment;

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