One, groundwater
Groundwater is the commonnest problem in deep foundation construction, it gives dig aperture picket construction to bring a lot of difficulty artificially. The water in aquifer destroyed his to balance position when excavate, make the static water all round fills picket hole inside, affected the normal construction that digs aperture picket artificially thereby, if encounter construction of layer of dynamic and hydraulic earth, not only excavate is difficult, protect mural concrete repeatedly easy also by hydraulic erode penetrable, produce problem of picket body quality. If was encountered fine layer of sandy soil of arenaceous, pink, below the action of pressure water, happen extremely easily also stream arenaceous with well leakage phenomenon.
When 1. groundwater amount is not large
Can choose sumbersible pump pump water, excavate of edge of edge pump water, irrigate in time into aperture hind build corresponding paragraph concrete protects a wall, continue next below one paragraph construction.
When 2. water amount is larger
Should use pump water of water pump of construction aperture oneself, when not easy also excavate, answer to consider from construction order, adopt right all round the pump water when picket Kong Tong, in order to reduce excavate aperture inside emerge water quantity, adopt the method of alternant loop construction, constituent arrangement is reasonable, can achieve very good result.
3. is right the not quite deep picket that dig hole
But attendant all around reasonable decorate precipitation of unified light-duty tube well billabong, cover an area of to fundamental plane bigger when, the platoon that also can increase precipitation tube well is counted, can solve commonly.
The environment when 4. pump water is affected
Sometimes construction surroundings is special, it is the surroundings when taking out groundwater pass in and out, the influence such as infrastructure is more, do not permit absoluteness pump water; 2 be all round Jiang Sha, laky, marsh waits, achieve pump water goal impossibly without limit. Because this all should take reliable step before pump water. Handling the method with this kind of the most active issue is to cut off fountainhead, close canalage. When picket aperture is more shallow, usable sheet pile closes; When picket aperture is deeper, form heavy curtain to block water with bore pressure grouting, it is in order to assure when normal pump water, achieve normal excavate.
Dig aperture picket groundwater artificially
2, flow arenaceous
When digging Kong Zaikai artificially, if encounter fine arenaceous, when powdery arenaceous layer is geological, plus the action of groundwater, form extremely easily stream arenaceous, serious when can produce well leakage, cause quality accident, because this should take effective and reliable step.
When 1. shedding arenaceous circumstance is lighter
Effective method is to shorten the excavate deepness of this one loop, will normal 1m controls a paragraph, shorten for 0.5m, reveal time with reducing those who dig a hole wall, undertake in time protecting mural concrete perfusion. Collapse when hole wall fall, have cover or daub with plaster arenaceous when flow into and cannot forming picket hole, earth of usable spin bag piles gradually, those who form picket hole outside wall, control make sure wall satisfies design requirement.
When 2. shedding arenaceous case is more severe
Commonly used method is sleeve issueing steel, steel sleeve and the steel that protect a wall to use velar board is similar, it is a diameter with aperture external diameter, can divide into arc of 4-6 Duan Yuan, plus proper rib, buckle join with bolt or annulus of reinforcing steel bar each other, in excavate 0.5m left and right sides, can divide piece load sleeve, thorough hole bottom not less than 0.2m, the side outside inserting upside concrete to protect a wall is not less than 0.5m, the standard is raised namely after outfit pouring the concrete that protect a wall, if put sleeve hind to flow arenaceous still go up emerge, can adopt the method that hole bottom closes with concrete namely after outstanding gouge, after waiting for concrete to condense, kong Xin the concrete Qing Dynasty of place certains in order to form picket hole. Also can use this kind of method, apply the concrete that already finished to protect a wall most issue Duan Zuan big, make aperture tilt to protect a wall to lower level beyond, infiltrate the oar is in charge of, pressure irrigates affusion slop, make bottom soil some better, rise all round the waterproof sex that reachs bottom soil, shed arenaceous phenomenon in order to solve.
3, silty qualitative earth layer
In encounter silty when the weak earth layer such as qualitative earth layer, general and usable wood pattern plate of square, board block, the excavate deepness that wants this paragraph to shorten, seasonable and pouring concrete protects a wall, this square board wants a wood that block to infiltrate along periphery bottom not less than 0.2m are deep, the concrete that upside embeds upside already had been irrigated protects a wall from the back, but inclined to place, double platoon decorates mutual and retrorse across, can achieve raise very well block the effect.
4, of picket body concrete irrigate build
1. removes the effect of water
1.Seeper of 1 hole bottom
Irrigate concrete of the body that build stake to basically should make sure its accord with design intensity, want to assure the uniformity of concrete, close-grained sex, cooperate more close-grained than mixing sex because of what this prevents the seeper inside aperture to affect concrete.
Irrigate the seeper inside dry hole should be smoked before building, the sumbersible pump of pump water wants furnish refluent a powerful person, when assuring to put forward water pump, water of the remain in causing pump water to be in charge of flows into picket aperture again inside. If the water inside aperture is smoked,do not work, after putting forward water pump, can mix with partial doing concrete compound or dry cement shop enter hole bottom, next again pouring concrete.
If amount of hole bottom water is large, the method that cannot adopt pump water really is solved, the construction of picket body concrete ought to adopt underwater to irrigate build construction technology.
Water of ooze of 1.2 hole wall
To water of hole wall ooze, not allow to ignore, because picket body concrete is irrigated,build time longer, if ooze water is overmuch, will affect concrete quality, reduce picket body concrete strength, can irrigate in picket body concrete waterproof is used to close before building leakage place. Measure bigger Kong Ke to infiltrate with chock to giving water, reoccupy waterproof closes all round, or in concentration slack part embeds sluicing is in charge of, mount valve, valve is opened to let current go out when construction picket aperture, when irrigating concrete of the body that build stake, shut again, also can solve its to affect the issue of quality of picket body concrete so.
2. assures the close-grained sex of picket body concrete
The close-grained sex of picket body concrete, it is the requirement that makes sure concrete achieves design intensity. Irrigate built close-grained sex to assure picket body concrete, use commonly string shed the makings below the canister to reach statified brace up pound irrigate built method, among them irrigate building career is crucial, namely do one's best finishs concrete of body of a picket to irrigate inside the shortest time build, be in especially when having case of subterranean pressure water, the requirement centers enough concrete short time to be irrigated, so that precede,concrete oneself weight pins the infiltration of current.
The picket body that is more than 10m to deepness gets offline, the pressure area of the weight of the wallop that the fall that can rely on concrete oneself forms and concrete oneself makes his close-grained, this part concrete can need not brace up pound, experience proves, picket body concrete can satisfy uniformity and close-grained sex. And speed excel uses string of construction drifting a canister, irrigate to concrete of picket body upside build the construction method with should be adopted regular, because general upside has groundwater to affect rarely, irrigate build career need not very fast, also cannot use the special construction method of free whereabouts.
5, reasonable arrangement construction is ordinal
Reasonable arrangement digs the construction order of aperture picket artificially, have main effect to reducing construction difficulty, want to plan as a whole seriously in the programme of construction, according to actual condition reasonable arrangement.
Below probable condition, first the picket aperture with more shallow construction, hind the picket aperture with a few deeper construction. Because general picket Kong Yu is deep, difficulty heals relatively big, after more shallow picket aperture construction, have consolidate effect to the stability of upside earth layer, also reduced the pressure when deep aperture construction. In the construction in aquifer or the earthy layer that have the pressure that use water, should first construction periphery (or the place that greet water) picket aperture, after concrete of aperture of this part stake protects a wall to finish, can withhold a few picket aperture not to irrigate concrete of the body that build stake first, and as catchment well, with convenient other aperture construction. The construction speed that assured picket aperture and the quality that become hole.
