A cut-off water process for a concrete underground structure

Abstract: A cut-off water process for a concrete underground structure (1) including the following steps; drilling a through-hole (2) at each water-leaking portion of a concrete wall (1) for inserting a pipe (3) with a valve (9,10); temporarily interrupting the spouting water by shutting off the valve (9,10); grouting cement slurry mixed with an accelerating agent through the pipe (3) to push out in the outer void of said concrete wall (1) so as to develop a cement hardened layer; and cutting away the projecting end of the pipe (3), wherein the method further including the following steps; leaving the work about for one day as it is; removing unhardened cement in the pipe, from which water is still leaking; filling cement powder, preferably mixed with a cohesive filler and an accelerating agent with the help of a cement filling gun to push out in the said pipe so as to form a heap thereon; repeatedly imparting a strong impacting stress and filling up with cement powder; and finally finishing the inner surface of the concrete wall in even surface level with cement paste by a trowel.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cut-off water process for cutting off underground-water leaking from a concrete wall into an inner space of an underground structure such as a tunnel, sewageworks, pipe utility conduit, a fire preventive water tank, a cellar and the like. In the recent urban districts deep-underground (geo-front) structures have increasingly been constructed, while water-leakage into the underground structure has accordingly become a serious problem. Inherently cities are developed along river basins in any countries. For example, in Tokyo urban areas are formed both sides of many rivers such as the Sumida River, the Edo River, and so on. In addition there are complex underground water veins around such rivers. Furthermore, there are many factors causing water-leakage in the deep underground structures such as underground facilities of waterworks and sewageworks, new underground water veins emerging due to a concentrated heavy rain water obstructed by a ground surface or underground structures, and the like. Against such water leakage upon the cause of construction such a concrete underground structure, various cut-off water methods have certainly been taken in advance , for example to joint and crack portions of a concrete structure and the like. As other existing cut-off water methods, there are methods having the following steps: cutting off a concrete portion at water leakage portion of the existing structure in a V or U shaped manner; filling up or applying with a cut-off water materials in the said V or U shaped cut portions, and a cut-off water method by filling up joints and cracks in the water leaking surface side with any other swelling resins. However, even if such temporary cut-off water treatments or mending works had been done and were successful, in the lapse of time or by the vibrations thereafter water leakage would often emerge at the same portions again. Furthermore, by repeating such mending works said V or U shaped cut portions would be enlarged, which causes the strength of the concrete wall of the underground structure to be weakened. 2. Description of the Related Art In order to solve a problem as mentioned above, the inventor of the present application developed, as a cut-off water system, a method for grouting in water leaking portions with cement slurry under low pressure (refer to JP-B-5046413). According to this method the concrete wall of a underground structure such as a tunnel and the like is firstly provided with a through-hole extending from the inside to the outside thereof at the water leaking portions. Then a pipe is inserted into the through-hole, said pipe having a valve. For the purpose of cutting off a large amount of spouting water, the valve of the pipe is temporarily shut off before cement slurry is grouted through the charging end of the pipe into the through-hole under pressure of 3-5 kg/cm 2 by a grouting pump to push out into the opposite outer void of the concrete wall. Finally cement slurry is mixed with an accelerating agent, and cement particles are adhered to the water leakage portions of the outer surface of the concrete wall by water pressure to form a cement hardened layer extending over some extent of area of the outer surface whereby water leakage is cut off. After the grouted cement have hardened, the end of the pipe inwardly protruding from the inner surface of the concrete wall is cut away, and the inner surface is finished with finishing material in even surface level of concrete wall. Thus the cut-off water work is completed. However, when cement is not sufficiently hardened or a certain water leakage is still emerged, it is required to completely cut off the water leakage again. SUMMARY OF THE INVENTION The object of the present invention is to provide with a process for completely cutting off water leakage, after which any water leakage would never emerge. In order to achieve this object, a method of sealing a concrete underground structure against water leakage according to the present invention comprises the following steps; drilling a through-hole extending from the inside to the outside of a concrete wall of said underground structure at each water-leaking portion thereof; inserting a pipe into each said through-hole, each pipe including a valve; temporarily interrupting a large amount of water spouting from a charge end of said pipe by shutting off said valve; grouting cement slurry-under low pressure through said pipe into said through-hole and pushing it out onto the outer surface of said concrete wall in the underground by a grouting pump, while mixing an accelerating agent into said cement slurry and adhering cement particles onto said outer surface of said concrete wall at said water leaking portion whereby said outer surface of said concrete wall is coated with a cement hardened layer extending over some extent of area; and cutting away the end of said pipe inwardly projecting from said inner surface of said concrete wall toward the inner space of said underground structure: wherein said method further comprises the following steps; leaving the work for about one day as it is; removing unhardened cement in the spout of said pipe, from which water is still leaking; filling cement powder, preferably mixed with a cohesive filler and an accelerating agent, if desired, with the help of a cement filling gun to push it out into the spout of said pipe and into said through-hole so as to heap up powder the inner surface of the concrete wall; imparting a strong impacting stress by an impacting tool or a hammer toward said filled cement powder from the inside of said concrete wall to consolidate and tightly fill it up into the spout of said pipe and said through-hole; repeating several times such an operation around the said spout of pipe leaking portion; and finally finishing the inner surface of said concrete wall at said water leaking portion with cement paste. In case of a large amount of spouting water it is preferred to mix a required amount of clay as a cohesive filler into the pipe with pressure before the step of filling cement powder. After cement powder is filled with the help of a filling gun to form a heap thereon, a strong impacting stress is applied to said filled and heaped cement powder by an impacting tool or a hammer. In case that water leakage portion is extended along a crack of the concrete wall, it is preferred to use sodium alginate (industrial laver) powder as a cohesive agent mixed with said cement powder for full penetration. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be explained in further detail hereinafter, by referring to the preferred embodiment illustrated in the accompanying drawings, wherein: Fig. 1 is a schematically illustrated view at the first stage of cut-off water work according to a process of the present invention; Fig. 2 is a schematically illustrated view at the step of filling up with cement powder with the help of a cement filling gun according to a process of the present invention; Fig. 3 is a schematically illustrated view at the step of compacting cement powder by a compacting tool or a hammer according to a process of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Fig. 1, a cut-off water method for a concrete underground structure according to the present invention is hereinafter described. According to the process of the present invention, the concrete wall 1 of the underground structure is provided with a through-hole 2 extending from the inside to the outside of the concrete wall at water leakage portion. A pipe 3 is inserted into the through-hole 2, said pipe 3 connected to hoses 4 which supply the through-hole 2 from a slurry mixed tank 5 and an accelerating agent tank 6 through grouting pumps 7, 8 and valves 9, 10 with a mixture of the cement slurry and the accelerating agent at a predetermined mixing ratio through the pipe 3 to form a hardened cement layer on the outer surface of the concrete wall 1 spreading over some extent of grouting area. Then the end of pipe 3 inwardly projecting from the inner surface of the concrete wall 1 is cut away along the inner surface of the concrete wall 1, and thereafter the work is left as it is for about one day. If a water leakage in the cut-away pipe still remains, unhardened cement is removed from the pipe and the through-hole before cement powder mixed with an accelerating agent is filled up in the spout of the pipe 3 with the help of a cement filling gun 11, and heaped up onto the inner surface of the concrete wall as shown in Fig. 2. Furthermore, a strong impacting stress is applied, as shown in Fig. 3, toward the filled cement powder mixed with the accelerating agent from the inside of the concrete wall 1 by an impacting tool 12 such as an electric pick hammer or a pneumatic hammer, and more and more cement powder mixed with the accelerating agent is filled up and compacted within the spout of the pipe and the through-hole. Finally such a repeatedly filled up portion is consolidated and finished with cement paste at the even surface level of the concrete wall 1. The type of cement firstly grouted as cement slurry may be varied according to the water leakage conditions. For example, at the portion where a water leakage rate is very small and in such an extent that a small amount of water oozes out of the inner surface of the concrete wall, a normal portland cement having a slow setting time is used, and then anyone of sodium bicarbonate group is used together as a hardening accelerator. At the portion where a large amount of water leakage is emerging, more than 100 liter per minute such as spouting water and spring water, super fine particle cement (average size of 4 µ) is used together with a weak acid silica sol as an accelerating agent, whereby gelatinization time is shortened within two minutes and cement can be hardened extremely in a short time to effectively cut off the water leakage. In the case of a middle amount of water leakage such as a spring water, super early strength cement (jet cement, so to speak, as one-hour cement) is used together with a setting retarder, whereby the cut-off water effect can be enhanced. At the portion where a water leakage is spreading over a large extent, and a very large amount of water is leaking, necessary numbers of suitable masses of rounded clay are firstly pressed into the water leaking portion, and thereafter cement powder is filled up with the help of a filling gun and is heaped on the inner surface of the concrete wall, while the filled cement is strongly compacted by an impacting tool or a hammer. Further at the portion where a water leakage extends along a crack of the concrete wall, a mixture of cement and industrial laver as a cohesive agent, for example in a ratio of 4 for industrial laver to 6 for cement is used. Such laver is suspended in water, penetrates along the whole cracks emerging the water leakage, and then expands thereat while it becomes aggregate of cement so that the cement bridge the water leakage portions. Furthermore, even if the cohesive agent penetrates into an underground water during the cut-off water work, it never becomes a factor of pollution as found in other conventional organic accelerating agent. Some successful examples according to the cut-off water method for a concrete underground structure of the present invention will be now described. Example 1 A normal portland cement powder mixed with sodium bicarbonate of 10% by weight was filled up, and compacted by an electric pick hammer as an impacting tool, which operation was repeated three times, whereby the amount of totally used cement was 550g and the cut-off water work was accomplished, and successful. Example 2 Jet cement as a super early strength cement was used, filled up, and compacted by an electrical pick hammer, which operation was repeated three times, whereby the amount of totally used cement was 500g, and thereafter finished in even surface level of concrete wall by a trowel. As a result, any water leakage could not recognized thereafter. Example 3 Although after grouting of cement slurry the valve was shut off, the work was left as it was for one day, and then the projecting end of pipe was cut away, unhardened cement dripped down together with spring water. Then the unhardened cement within the pipe was removed, twelve egg-sized rounded clay masses were pressed into the pipe so as to temporarily interrupt the water leakage before a normal portland cement powder was filled up with the help of a cement filling gun, and the filled cement was compacted with the help of an electric pick hammer, which operation was repeated three times, whereby the amount of totally used cement was 320g. After the lapse of one day the result of the cut-off water work was observed to be perfect in its cut-off water effect. Example 4 Cement powder mixture, in which a normal portland cement of 70% by weight was mixed with sodium alginate powder of 30% by weight, was filled up into the pipe with the help of a cement filling gun, and the filled cement powder was compacted by an electric pick hammer, further the space of pipe produced by the said operation was filled up with cement powder again, then compacted in the same way, which operation was repeated four times to accomplish consolidation filling, whereby the amount of totally used cement was 600g. Finally the inner surface of the concrete wall was finished in even surface level of concrete wall by a trowel. As a result no water leakage was recognized at the cut-off water work, so that it's effect could be confirmed to be good. According to such an method as described above, without any special equipment and material cut-off water work is effectively accomplished only by conventional equipments and materials used usually in civil engineering works, with low cost, and without any releakage of water from the same portion thereafter. Especially, when sodium alginate (industrial laver) is used as a cohesive agent mixed with cement powder, the material is low cost, performs an remarkable effect, and involves no environmental pollution. Further according to the method of the present invention the step of compacting cement powder mixed with an accelerating agent and a cohesive agent causes a mechano-chemical effect to powder particles so as to enhance the strength of the resulting seal, which contributes to an initial perfect cut-off for water leakage and a subsequent hardening of cement powder gradually absorbing water.

Claims: A method of sealing a concrete underground structure against water leakage comprising the following steps; drilling a through-hole (2) extending from the inside to the outside of a concrete wall (1) of said underground structure at each water-leaking portion thereof; inserting a pipe (3) into each of said through-holes, each pipe including a valve; temporarily interrupting a large amount of water spouting from a discharge end of said pipe by shutting off said valve; grouting cement slurry under low pressure through said pipe into said through-hole and pushing it out onto the outer surface of said concrete wall against the underground water pressure by a grouting pump (7,8), while mixing an accelerating agent into said cement slurry and adhering cement particles onto said outer surface hair cracks of said concrete wall at said water leaking portion whereby said outer surface of said concrete wall is coated with a cement hardened layer extending over some extent of area; and cutting away the end of said pipe inwardly projecting from said inner surface of said concrete wall to the inner space of said underground structure, wherein the above mentioned method further comprises the following steps; leaving the work for about one day as it is; removing unhardened cement in the spout of said pipe, from which water is still leaking; filling cement powder, preferably mixed with a cohesive filler and an accelerating agent, if desired, under pressure with the help of a cement filling gun (11) into the said spout of said pipe and further pushing said cement powder out so as to form a heap the inner surface of the concrete wall; imparting a strong impacting stress by an impacting tool (12) onto said filled cement powder in the spout of the pipe to consolidate and tightly fill it up into said spout of said pipe and said through-hole; repeating several times such an operation in the space of the pipe produced by impacting; and finally finishing the compacted surface of said pipe at said water leaking portion with cement paste. A method as claimed in claim 1, wherein clay is used as said cohesive filler. A method as claimed in claim 1, wherein sodium alginate powder is used as said cohesive agent mixed with said cement powder. A method as claimed in claim 3, wherein said sodium alginate powder used as said cohesive agent is employed in a ratio of 30% by weight of sodium alginate to 70% by weight of cement powder.

Inventors: NAGAHAMA SHIGEO, NAGAHAMA, SHIGEO
Applicants: NAGAHAMA SHIGEO, NAGAHAMA, SHIGEO
Application year: 1995
Main classification: E02D31
IPC codes: E02D29, E02D31, E21D11, E04G23, E04B1