CN101130991A - Caisson cofferdam based on prepacked foundation bed - Google Patents

Abstract

The present invention discloses one kind of caisson coffer based on foundation bed grouting and its construction process. The caisson coffer is constructed through the following steps: digging foundation ditch and desilting, filling rubble and leveling, prefabricating and sinking caisson, grouting foundation bed, grouting curtain, etc. The present invention has the advantages of high stability, easy construction, saving in material, short construction period, less environmental influences, small coffer demolishing workload and low engineering cost.

Description

Rise the caisson cofferdam and the job practices thereof of slurry based on bedding

Technical field

The present invention relates to the cofferdam and the job practices of hydraulic structure, especially a kind of caisson cofferdam and job practices thereof that rises slurry based on bedding.

Background technology

In traditional dock work progress, interim cofferdam must be set, just can carry out the construction of dock agent structure, common double steel sheet-pile cofferdam, lattice shaped steel plate pile cofferdam arranged, throw the masonry dam cofferdam etc. of banketing, the cofferdam generally will account for a large amount of waters, and is costly; Expense accounts for about 10～15% of dock project total cost, and waste material was wasted time and energy in the dismounting in cofferdam again after the dock construction was finished.

Summary of the invention

The objective of the invention is not enough and a kind of caisson cofferdam and job practices thereof that rises slurry based on bedding that provide at prior art, it has good stability, easy construction, the cofferdam structure occupy-place is few, save the space, little to surrounding environment influence, and consumptive material is economized the duration weak point, construction costs is low, the little advantage of dismounting workload in cofferdam.

The object of the present invention is achieved like this:

A kind ofly rise the caisson cofferdam of slurry based on bedding, it is prefabricated caisson sinking to be carried out a liter slurry to bedding handle behind the riprap foundation at place, required cofferdam, constitutes liter carrying out curtain grouting below the slurry bedding again.

Job practices of the present invention comprises following concrete steps:

(1) excavating foundation trench and desilting

By designing requirement excavation foundation trench, and remove mud.

(2) bedding jackstone and leveling

Fill block stone throwing in foundation trench forms bedding, piece stone diameter of phi 80～Φ 200mm, and intensity is not less than 30Mpa, throws porosity after filling out more than 40%, thickness of subgrade bed 0.5～8m, and to base bed flattening.

(3) the prefabricated and sinking of caisson

By the prefabricated caisson of designing requirement, and in caisson pre-buried several grout pipes, the caisson transportation by driving to on-the-spot sinking on riprap foundation, and to carrying out backfill in the case.

(4) bedding rises slurry

In the caisson grout pipe, carry out the internal drilling of bedding stone riprap, and carry out pressure grouting.

(5) curtain grouting

Bedding carries out the boring of bedding concrete to batholith, and carries out pressure grouting after rising slurry formation concrete in grout pipe.

The present invention adopts bedding to rise the technology of curtain grouting under slurry, the bedding, form a kind of cofferdam structure with caisson, be suitable for the cofferdam of newly-built harbour, dock, it has good stability, easy construction, consumptive material is economized, and the duration is short, and is little to surrounding environment influence, the dismounting workload in cofferdam is little, the advantage that construction costs is low.

Description of drawings

Accompanying drawing is the embodiment schematic cross-section in cofferdam of the present invention

The specific embodiment

Embodiment

With the dock foundation ditch is 450m * 120m, and the degree of depth is 14m, and wherein the dash height is 13m, and the outside is the marine site, and the place geological conditions is that rock foundation is an example, and concrete construction sequence is as follows:

1, excavating foundation trench and desilting

Harbour position excavating foundation trench is to scar, and riprap foundation thickness is 2m, and bottom width is controlled at about 15m, removes mud.

2, bedding jackstone and smooth

The piece stone that diameter is 80～200mm is filled out in throwing in foundation trench, and void content is controlled at 40%, and the bedding both sides are provided with and keep off the packed rubble dam body of slurry, and cover with geotextiles, and the jackstone face flattens the extremely superfine surperficial mud scum of putting down and remove.

3, the prefabricated and sinking of caisson

The caisson width is 13m, high 12m, and length is 18m, pre-buried madjack pipe is several in the caisson, laterally establish 1～2 group, every group 2 row, longitudinal pitch 2～3m, caliber 120～150mm, caisson adopts water under the slideway, transportation by driving behind the scene sinking on bedding, beginning backfill mountain skin stone in case.

4, bedding rises slurry

After the interior backfill of caisson sinking and case, in madjack pipe, carry out the internal drilling of bedding stone riprap, the hole clearly of must pouring water, remove between the piece stone, at the bottom of the caisson and jackstone and riprap foundation bottom and rock between mud, madjack pipe can be led to into afterwards, in caisson riprap bedding, rise slurry,, mix an amount of water reducing agent and expansion agent in the slurries for improving mortar performance.Cement: adopt the 325# Portland cement, sand: middle fine sand, water: fresh water, the initial setting time is 8～10h.The mud jacking finishing control: reach 40% control by caisson bedding volume injection rate, grouting pressure reaches 1.5～2kg/cm ², continue perfusion 2 hours, require a pump one hole, do not allow a pump porous to construct simultaneously.

5, curtain grouting

Rise slurry after 5-7 days at bedding, utilize the bedding grout hole to carry out curtain grouting, at first manage internal drilling, bore the riprap foundation concrete then, pierce batholith at last, clear hole, the laggard rock curtain grouting of trying the water, the degree of depth of curtain grouting is decided by the broken crack of batholith in the geologic information degree of depth, the transmission coefficient control criterion is less than 5Lu, and make packer permeability test, if the aperture packer permeability test that has can not reach above-mentioned standard, boring 4m and mud jacking are downwards continued in this position, hole and adjacent holes position, reach design standard until packer permeability test.Grouting pressure is controlled at 2kg/cm ²About, continue perfusion a period of time.

After finishing above-mentioned construction, the packed clay dam body of heap is to+5.0m on caisson, to satisfy the flood control engine request, so far, the caisson cofferdam structure that caisset, liter slurry bedding, curtain grouting are formed is finished, after function is finished in the cofferdam, the cofferdam caisson of former harbour position then need not to remove, can directly be used as the harbour caisson, the cofferdam caisson of all the other positions should be removed, and can make other harbour caisson after caisson floats and use.

It is fine in conjunction with the grouting stagnant water effect that bedding of the present invention rises slurry, bedding liter slurry water-stop technology is that dock dry application worker has created condition under the caisson, bedding rises the slurry technology and has also created dock main body dry application worker condition for some because objective condition is not suitable for building the engineering in cofferdam, the present invention applies at several dock cofferings, has all obtained good stagnant water effect and economic benefit.

Claims (2)

1. one kind rises the caisson cofferdam of slurry based on bedding, it is characterized in that it is prefabricated caisson sinking to be carried out a liter slurry to bedding handle behind the riprap foundation at place, required cofferdam, constitutes liter carrying out curtain grouting below the slurry bedding again.

2. the job practices in the described cofferdam of claim 1 is characterized in that it comprises following concrete steps:

(1) excavating foundation trench and desilting

By designing requirement excavation foundation trench, and remove mud;

(2) bedding jackstone and leveling

Fill block stone throwing in foundation trench forms bedding, piece stone diameter of phi 80～Φ 200mm, and intensity is not less than 30Mpa, throws porosity after filling out more than 40%, thickness of subgrade bed 0.5～8m, and to base bed flattening;

(3), the prefabricated and sinking of caisson

By the prefabricated caisson of designing requirement, and in caisson pre-buried several grout pipes, the caisson transportation by driving to on-the-spot sinking on riprap foundation, and to carrying out backfill in the case;

(4) bedding rises slurry

In the caisson grout pipe, carry out the internal drilling of bedding stone riprap, and carry out pressure grouting;

(5) curtain grouting

Bedding carries out the boring of bedding concrete to batholith, and carries out pressure grouting after rising slurry formation concrete in grout pipe.