JPS582380A - Mud slurry composition for ground excavation - Google Patents

Abstract

PURPOSE:To prepare the titled composition having excellent salt resistance and mud-wall forming property, and unaffected by polyvalent metal ions, cement, etc., by adding a specific amount of a specific mixture of gum guaiac and xanthan gum to mud slurry. CONSTITUTION:The objective composition is prepared by adding a mixture composed of 95-50wt%, preferably 90-60wt% gum gauiac and 5-50wt%, preferably 10-40wt% xanthan gum to a mud slurry. The amount of the mixture is 0.01-2wt%, preferably 0.02-1wt% of water existing in the mud slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mud composition for ground excavation. More specifically, the present invention relates to a mud water composition for ground excavation that has excellent mud wall-forming properties by blending guar gum and xanthan gum in a certain ratio.

In conventional ground excavation methods, bentonite mud is the most widely used mud water, but it is inferior in mud water performance such as mud wall formation. For this reason, organic thickeners such as carboxymethyl cellulose sodium salt (CMC) and starch derivatives are used in combination, but these have low salt tolerance and
Because of this poor H stability, the viscosity decreases due to salts and polyvalent metal ions (e.g. calcium, magnesium, aluminum) contained in geological formations and groundwater, and the amount of dewatering increases significantly, resulting in poor mud wall formation. Deteriorate.

In particular, when creating muddy water using seawater or saturated salt water, it is sufficient to use muddy water mainly composed of bentonite, which inherently has poor swelling power in seawater or saltwater, or CMC'i, whose viscosity decreases significantly due to the presence of salts. Performance in slow muddy water cannot be achieved.

On the other hand, in the excavation method used in civil engineering foundation work, the ground is generally excavated using muddy water, then concrete is poured in and the muddy water inside is replaced by a comfleet truck to construct foundation piles and underground continuous walls. At this time, it is necessary that the muddy water does not cause abnormalities such as thickening, gelation, and precipitation due to strong alkaline cement, that is, it must have good stability against cement. However, if the bentonite mud is combined with the above-mentioned organic thickener, gelation occurs when it comes into contact with cement, and the performance of the mud deteriorates significantly.
It becomes impossible to reuse.

In addition to the above, attempts have also been made to use guar gum alone or xanthan gum alone as a thickening agent. However, in this case, when ordinary water is used, the performance is satisfactory as mud water, but when seawater or salt water is used together with inorganic clay, the mud water performance and cement stability are poor. be. In other words, since guar gum originally has the property of acting as a coagulant, it aggregates and coarsens clay particles in seawater or salt water, significantly worsening the dispersion stability of muddy water, resulting in poor mud wall formation. The muddy water performance is poor. Furthermore, the performance of muddy water becomes even worse due to the mixing of cement. On the other hand, xanthan gum has the disadvantage that its viscosity decreases due to the action of aluminum ions and the like. Also, depending on the type of inorganic viscosity used in combination, the viscosity of mud may increase due to the mixing of cement, sometimes causing gelation.

In order to eliminate the drawbacks of conventionally used mud, the present inventors have sought to overcome the drawbacks of mud, which has excellent salt resistance, is not affected by polyvalent metal ions or cement, and has the ability to form mud walls, etc. The present invention was achieved as a result of extensive research into muddy water compositions that fully satisfy the above performance requirements. That is, in the present invention, a mixture consisting of 95 to 50% by weight of guar gum and 5 to 50% by weight of xanthan gum is added to muddy water at a concentration of 0.01 to 50% by weight.
This is a mud water composition for ground excavation which has excellent mud wall forming performance and is made by adding 2% by weight.

In the present invention, guar gum is a natural polysaccharide present in the endosperm of seeds of guar bean, which is an annual leguminous plant.
Its chemical structure contains D-galactone and D-mannose in a ratio of 1:2 and has a molecular weight of approximately 200,000.

Xanthan gum is an exopolysaccharide produced by fermenting bacteria of the genus Xanthomonas in a glucose medium. Examples of these bacteria are Xanthomonanu cambestris, Xanthomonas phaseoli, Xanthomonanu cataero, and Xanthomonanumulpacealan.

Among them, the gum produced by Xanthomonas scabbestris is preferred. Although its chemical structure is complex, it is estimated to have a main chain structure of D-glucose, D-mannose, and glucuronic acid bound to pyruvate, acetate, etc., and its molecular weight is said to be about 2 million.

The formulations in this invention are based on the formulation.
guar gum and 5-50% xanthan gum, preferably 90-60% guar gum and 10-4% by weight
It consists of 0 weight xanthan gum.

When the amount of guar gum exceeds 95%, as in the case of guar gum alone, the clays coagulate and become coarse particles, resulting in poor dispersion stability of mud water, and as a result, the amount of dewatering increases significantly and mud wall formation is impaired. Deteriorate. In addition, the mixing of cement promotes coagulation and precipitation of inorganic clays, further increasing the amount of water removed. When the amount of xanthan gum exceeds 50%, the amount of water removed increases and the mud wall forming performance becomes poor. Guar gum 95
~50%.

Only when xanthan gum is blended in the range of 5 to 50 g, a mud water composition having excellent mud wall forming properties and good dispersion stability can be obtained.・In addition, it has good stability against cement. However, instead of guar gum, derivatives of guar gum (e.g. alkali metal salts of carpogysialylated guar gum, hydroxyalkylated guar gum, etc.)
When f: is used, muddy water performance and cement stability are poor.

The mud here is also called drilling fluid or stabilizing fluid, and is used in drilling methods for civil engineering construction foundation work such as underground continuous wall construction method, cast-in-place pile construction method, mud water pressure shield method, and oil poling. It is a fluid that The muddy water absorbs and dissipates the frictional heat between the excavator and the earth and sand, and also has the role of suspending the cut earth and sand in the muddy water and transporting it to the outside, as well as creating impermeable mud on the walls of the excavation hole. form a wall,
It plays a role in preventing ground collapse by preventing moisture in muddy water from dispersing into the strata and preventing moisture in the strata from entering the borehole.

Mud water includes 1) water itself (generally not called mud water or stable liquid), 2) aqueous solutions of organic thickeners such as CMC and starch derivatives, and 8) aqueous dispersions mainly composed of inorganic clays. However, generally an aqueous dispersion containing inorganic clay as a main ingredient is used.

The water used for muddy water may be general tap water, groundwater, seawater, or salt water. Bentonite is a clay,
Attapulgite, chrysotile-based anubest, and powdered clay are examples, and their types and production areas are particularly limited.

The amount of inorganic clay used is not particularly limited and can be changed as appropriate depending on the specific gravity of the muddy water required, but it is usually 8 to 60% by weight, preferably 5 to 40% by weight, based on the muddy water.

For muddy water, use trophumate as a dispersant if necessary.

condensed phosphates, lignin sulfonates, polyacrylates, etc.), pH adjusters, protective colloids.

Surfactants, preservatives, fungicides, fungicides, antioxidants.

It can also contain deodorants and the like.

The mud water composition for ground excavation of the present invention is made by adding a mixture of 95 to 505 to 50 weight % gum and 5 to 50 weight % xanthan gum to mud water.

The amount of this formulation added to the mud is in the water in the mud. If the amount added is less than 0.01% by weight, not only will the mud not have the necessary viscosity, but the amount of water removed will increase and the mud wall forming performance will deteriorate. If more than 2% by weight is added, the mud wall forming performance is further improved, but the viscosity of the mud increases, making it difficult to excavate.

When preparing the muddy water composition of the present invention, guar gum and xanthan gum may be blended in advance by dry mixing and added to the muddy water, or guar gum and xanthan gum may be separately added to the muddy water and then added to the muddy water. The muddy water composition may be prepared to obtain a blended product. The dry mixing device is not particularly limited as long as it can mix uniformly, and is usually a V-type mixer or a Nauta mixer.

A ball mill etc. can be used.

The mud composition for ground excavation of the present invention obtained in this way usually has a specific gravity of 1.02 to 1.85. Funnel viscosity 22
Maintains physical properties such as ~45 seconds (500 m/1500 m7: 25°C), dehydration amount of 20 m1780 minutes or less (81 $/m pressure). It is said that the thicker or thinner the cake and the lower the amount of dewatering, the better the mud wall formation performance. This dehydration amount can be said to be one of the most important factors in determining the quality of the mud/water composition.

In an embodiment in which ground excavation is performed using the muddy water composition of the present invention, a muddy water composition is first prepared by adding and mixing the composition of the present invention, inorganic clay, etc. to water in a tank. Next, the ground is excavated using an excavator while circulating this muddy water composition to the excavation part. In this case, the muddy water composition constantly fills the excavated area and facilitates excavation by absorbing frictional heat, dissipating heat, and lubricating the area, and forms an impermeable mud wall that causes the wall of the excavation to collapse. is prevented. After the prescribed excavation is completed in this manner, a reinforcing frame is appropriately inserted, concrete is poured from the bottom, and while muddy water overflows from the top, the excavation is filled with concrete to construct a pile or wall. The muddy water that replaced the concrete is returned to the tank and reused.

The muddy water composition of the present invention has various features as described below. For example, (1) A muddy water composition containing the present formulation has excellent dispersion stability of inorganic clays.

(2) The mud water composition of the present invention has a small amount of water dewatered, and has excellent mud wall-forming properties, that is, the ability to prevent collapse of an excavated hole.

(3) Since the present formulation is not affected by salts, the muddy water composition of the present invention can be mixed with seawater or salt water.

Furthermore, even if underground salt water flows in during excavation, the physical properties of the mud (dispersion stability, amount of water removed, etc.) do not change.

(4) Even if the muddy water composition of the present invention is mixed with cement etc.,
The physical properties of mud (dispersion stability, amount of water removed, etc.) hardly change. This also applies to muddy compositions obtained using seawater or salt water.

Therefore, it can be used repeatedly.

(5) The muddy water composition containing the formulation according to the present invention exhibits the necessary viscosity as muddy water even when the present formulation is added in a smaller amount.

(6) Both guar gum and xanthan gum are used as food additives, so they are safe.

(7) In the muddy water composition of the present invention, powdered clay that can be obtained at low cost can be used as the inorganic clay, so it is economical as a whole. Although powdered clay is commercially available at low cost, it has rarely been used in the past because of its poor swelling ability in water.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Note that parts and parts in the examples are based on weight. The test methods in Examples and Comparative Examples are as follows.

(1) Funnel viscosity (FV): Measured with a 500cc funnel viscometer. The unit is seconds.

(2) Dehydration amount: Using a filter according to API standards, 8
Amount of water removed after 80 minutes under a pressure of 97 m.

Unit: ml! .

(3) Cake thickness: Measure the cake on the filter paper with a caliper.

Unit: 1n11° (4) Dispersion stability: 100m7 of muddy water was placed in a 100m7 graduated cylinder and observed after being allowed to stand for 3 days. When 5 ml or more of transparent supernatant water was formed in the upper part, it was judged as poor, when it was 1 to 5 ml, it was judged as slightly poor, and when there was no supernatant water and it was uniformly dispersed, it was judged as good.

(5) Stability with cement: 1 part of Portland cement was added to 100 parts of muddy water, thoroughly mixed, and the muddy performance was measured one day later.

Example I Using a V-type mixer, blended products were prepared in which the ratios of guar gum and xanthan gum were varied as shown in Table 1.

Table 1 Add 500ml of 4% saline solution to a 10100O juice mixer.
and 75 parts of powdered clay were added thereto, and after stirring for 2 minutes, 2 parts of blended products A to D shown in Table 1 were separately added thereto, and the mixture was further stirred for 5 minutes to prepare a muddy water composition. . The results of measuring the performance of these muddy waters are shown in Table 2. For comparison, guar gum, xanthan gum,
, CMC (degree of etherification 0.6) and 0.4 parts of formulation E in Table 1 were used, but the results of muddy water compositions prepared in exactly the same manner are also shown.

Example 2 Seawater (collected in the Seto Inland Sea + Cl content 21,000pp
m) A muddy water composition was prepared in the same manner as in Example 1 using 50 parts of bentonite from Gunma and 2 parts of blended products A, B, C or D listed in Table 1 of Example 1. Table 8 shows the results of measuring these muddy water performances.

For comparison, guar gum and xanthan gum.

The performance of muddy water compositions containing 0.5 parts of sodium tripolyphosphate as a dispersant in combination with 2 parts of each of CMC or Blend E was also measured, and the results are shown in Table 8.

θQ Example 8 The same procedure as in Example 1 was carried out using 500 parts of tap water, 80 parts of bentonite produced in Yamagata, and 2 parts of blended products B, C, or Do listed in Table 1 of Example 1 according to the present invention. The results of preparing muddy water compositions and measuring their muddy performance are summarized in the fourth section.
Shown in the table. For comparison, the results of muddy water using CMC, 82 parts of blended product EO, and 0.4 parts of CMC are shown.

Table 4

Claims (1)

[Claims] A formulation consisting of 1.95-50% by weight of guar gum and 5-50% by weight of xanthan gum was added at 0.0% to muddy water.
A mud water composition for ground excavation with excellent mud wall forming performance, which is obtained by adding 1 to 2% by weight.