A construction method for a cutter suction dredger to excavate complex soil

Abstract

The present invention discloses a construction method for a cutter suction dredger to excavate complex soil masses, which includes the following steps: Step 1, first conduct geological exploration on the construction area to be excavated; Step 2, the cutter suction dredger is in place, and the silt on the geological surface layer is excavated, and a 1-2-meter-thick silt bottom layer at the interface between the silt and the clay is reserved without excavation; Step 3, excavate the surface layer of the clay layer, and adopt the method of mixing and excavating the 1-2-meter-thick silt bottom layer reserved during silt excavation and the 2-meter-thick clay surface layer; Step 4, adopt the method of mixing and excavating the remaining bottom layer of the clay and the 1-2-meter-thick surface layer of medium coarse sand; Step 5, excavate the medium coarse sand, and the excavation depth of the medium coarse sand is carried out in multiple layers according to the thickness of the medium coarse sand and the scale of the cutter suction dredger. The construction method of the present invention can greatly improve the conveying efficiency of clay in complex geology, reduce the risks of pipe blockage and pipe explosion, and significantly shorten the construction period.

Description

Technical Field

[0001] The present invention relates to a construction method for a cutter suction dredger to excavate complex soil. Background Art

[0002] During the dredging process using a cutter suction dredger, when excavating different soil types in a cross-section, especially when there is a clay layer, it will cause difficulties in filling and often result in pipe blockage, greatly reducing the construction efficiency, increasing the construction period, and being unfavorable for engineering construction. Taking a certain project in the coastal area as an example, the geological structure of the filling and soil-taking area from top to bottom is: silty soil, clay, medium and coarse sand; due to the different properties of these three types of soil, namely silty soil, clay, and medium and coarse sand, there are also significant differences in the conveying efficiency of the soil suction pipeline. Silty soil and medium and coarse sand are easy to convey, while clay has high viscosity and adhesiveness and is extremely likely to adhere to the pipe wall in large quantities during conveying, causing pipe blockage. Therefore, when a cutter suction dredger excavates and conveys complex soil, not only is the efficiency greatly reduced, but also pipe blockage is very likely to occur. Once pipe blockage occurs, a large amount of manpower, material resources, and time will be consumed for pipe dredging. Currently, there are mainly three common solutions: 1. Change the cutting thickness of the cutter to reduce the amount of dredged soil and the mud pumping volume of the mud pump; 2. Change the forward movement distance and cross movement speed of the excavated clay to control the mud concentration inhaled by the mud pump; 3. Reasonably arrange the pipeline to avoid uneven pipeline arrangement, too many elbows, and large climbing angles, etc., so as to reduce the conveying resistance of the pipeline. Currently, the most commonly used is the first method, but using this method will greatly reduce the working efficiency of the dredger. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a construction method for a cutter suction dredger to excavate complex soil, which can greatly improve the conveying efficiency of clay in complex geology, reduce the risks of pipe blockage and pipe explosion, and significantly shorten the construction period.

[0004] The purpose of the present invention is achieved as follows: A construction method for a cutter suction dredger to excavate complex soil, comprising the following steps:

[0005] Step 1, first conduct geological exploration on the construction area to be excavated, and determine the soil layer distribution and thickness in the construction area according to the geological exploration results;

[0006] Step 2, the cutter suction dredger is in place, and the silt on the geological surface is excavated. The excavation depth of the silt is carried out in multiple layers according to the thickness of the silt and the scale of the cutter suction dredger, and a 1 - 2-meter-thick silt bottom layer is reserved without excavation at the interface between the silt and the clay;

[0007] Step 3, excavate the surface layer of the clay layer, and use the method of mixed excavation of the 1 - 2-meter-thick silt bottom layer reserved during the silt excavation and the 2-meter-thick clay surface layer for excavation;

[0008] Step 4: When there is clay with a thickness less than 4 meters in the geological structure, adopt the method of mixing and excavating the remaining clay layer with the 1-2-meter-thick medium-coarse sand surface layer;

[0009] When there is clay with a thickness greater than 4 meters in the geological structure, in the middle of the clay, adopt the method of reducing the cutting thickness of the cutter head and reducing the mud concentration of the mud pump for excavation, and leave a 2-meter-thick clay bottom layer at the interface between the clay and the medium-coarse sand unexcavated, and then adopt the method of mixing and excavating the 2-meter-thick clay bottom layer with the 1-2-meter-thick medium-coarse sand surface layer;

[0010] Step 5: Excavate the medium-coarse sand, and the excavation depth of the medium-coarse sand is carried out in multiple layers according to the thickness of the medium-coarse sand and the scale of the cutter suction dredger.

[0011] The construction method of the cutter suction dredger for excavating complex soil in the present invention has the following characteristics compared with the prior art:

[0012] When using the conventional method for excavation, the transportation efficiency of silt is about 3000 m 3 / h, the transportation efficiency of clay is about 1000 m 3 / h, and the transportation efficiency of medium-coarse sand is about 2000 m 3 / h; after adopting the excavation method of the present invention, when silt and clay are excavated mixedly, the transportation efficiency can reach 70%-80% of the transportation efficiency of pure silt, about 2000 m 3 / h; when clay and medium-coarse sand are excavated mixedly, the transportation efficiency can reach 70%-80% of the transportation efficiency of medium-coarse sand, about 1500 m 3 / h; therefore, compared with the method of simply excavating clay, the construction method of the present invention can greatly improve the transportation efficiency of clay in complex geology, reduce the risks of pipe blockage and pipe explosion, and greatly shorten the construction period. The geological characteristics applicable to the construction method of the present invention are widely distributed in the coastal areas of our country, so it has wide applicability in excavating complex stratified soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a flow chart of the construction method of the cutter suction dredger for excavating complex soil in the present invention;

[0014] Figure 2 is a distribution map of geological soil layers explored after step 1 in the construction method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be further described below in conjunction with the drawings.

[0016] Please refer to Figure 1 and Figure 2 , the construction method of the cutter suction dredger for excavating complex soil in the present invention includes the following steps:

[0017] Step 1: First, conduct a geological exploration of the construction area to be excavated, and determine the soil layer distribution and thickness in the construction area according to the geological exploration results;

[0018] Step 2: Position the cutter suction dredger and excavate the silt on the geological surface layer. The excavation depth of the silt is carried out in multiple layers according to the thickness of the silt and the scale of the cutter suction dredger, and a 1 - 2 - meter - thick silt bottom layer is reserved at the interface between the silt and the clay without excavation, which is convenient for the subsequent excavation of the clay to form a mixed transportation of the silt and the clay, improving the transportation efficiency of the clay and reducing the risks of pipe blockage and pipe explosion;

[0019] Step 3: Excavate the surface layer of the clay layer, and adopt the method of excavating the 1 - 2 - meter - thick silt bottom layer reserved during the silt excavation and the 2 - meter - thick clay surface layer in a mixed way;

[0020] Step 4: When there is a clay layer with a thickness less than 4 meters in the geological structure, adopt the method of excavating the remaining bottom layer of the clay and the 1 - 2 - meter - thick medium - coarse sand surface layer in a mixed way, which can improve the transportation efficiency of the clay and reduce the risks of pipe blockage and pipe explosion;

[0021] When there is a clay layer with a thickness greater than 4 meters in the geological structure, in the middle part of the clay, adopt the method of reducing the cutting thickness of the cutter and lowering the mud concentration of the mud pump for excavation, and a 2 - meter - thick clay bottom layer is reserved at the interface between the clay and the medium - coarse sand without excavation, and then adopt the method of excavating the 2 - meter - thick clay bottom layer and the 1 - 2 - meter - thick medium - coarse sand surface layer in a mixed way, which can improve the transportation efficiency of the clay and reduce the risks of pipe blockage and pipe explosion;

[0022] Step 5: Excavate the medium - coarse sand layer, and the excavation depth of the medium - coarse sand is carried out in multiple layers according to the thickness of the medium - coarse sand and the scale of the cutter suction dredger.

[0023] In this embodiment, the geological soil layer distribution detected in Step 1 is as follows: from top to bottom, there is a 10 - meter - thick silty soil layer, a 2 - 4 - meter - thick clay layer, and a 2 - 4 - meter - thick medium - coarse sand layer;

[0024] Step 2: Position the cutter suction dredger and excavate the silt on the geological surface layer. The excavation depth of the silt is carried out in 3 layers according to the thickness of the silt and the scale of the cutter suction dredger, with 1 layer excavated each time, and a 1 - 2 - meter - thick silt bottom layer is reserved at the interface between the silt and the clay without excavation;

[0025] Step 3: Excavate the surface layer of the clay layer, and adopt the method of excavating the 1 - 2 - meter - thick silt bottom layer reserved during the silt excavation and the 2 - meter - thick clay surface layer in a mixed way;

[0026] Step 4: Adopt the method of excavating the 2 - meter - thick clay bottom layer and the 1 - 2 - meter - thick medium - coarse sand surface layer in a mixed way;

[0027] Step 5: Excavate medium coarse sand. The excavation depth of the medium coarse sand is carried out in multiple layers according to the thickness of the medium coarse sand and the scale of the cutter suction dredger.

[0028] The above embodiments are only for illustrating the present invention and not for limiting the present invention. Those skilled in the relevant technical fields can also make various transformations or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention and should be defined by each claim.

Claims

1. A construction method for a cutter suction dredger to excavate complex soil, characterized in that, it includes the following steps: Step 1, first conduct a geological exploration of the construction area to be excavated, and determine the soil layer distribution and thickness in the construction area according to the geological exploration results; Step 2, the cutter suction dredger is in place, and the silt on the geological surface layer is excavated. The excavation depth of the silt is carried out in multiple layers according to the thickness of the silt and the scale of the cutter suction dredger, and a 1-2-meter-thick silt bottom layer at the interface between the silt and the clay is reserved without excavation; Step 3, excavate the surface layer of the clay layer, and use the 1-2-meter-thick silt bottom layer reserved during the silt excavation and the 2-meter-thick clay surface layer for mixed excavation; Step 4, when there is clay with a thickness less than 4 meters in the geological structure, use the remaining bottom layer of the clay and the 1-2-meter-thick medium-coarse sand surface layer for mixed excavation; When there is clay with a thickness greater than 4 meters in the geological structure, in the middle of the clay, use the method of reducing the cutting thickness of the cutter head and reducing the mud concentration of the mud pump for excavation, and reserve a 2-meter-thick clay bottom layer at the interface between the clay and the medium-coarse sand without excavation, and then use the 2-meter-thick clay bottom layer and the 1-2-meter-thick medium-coarse sand surface layer for mixed excavation; Step 5, excavate the medium-coarse sand, and the excavation depth of the medium-coarse sand is carried out in multiple layers according to the thickness of the medium-coarse sand and the scale of the cutter suction dredger.

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