CN114934776A - Construction method for inhibiting frost heaving and thaw collapse of water-rich geology - Google Patents
Construction method for inhibiting frost heaving and thaw collapse of water-rich geology Download PDFInfo
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- CN114934776A CN114934776A CN202210592842.5A CN202210592842A CN114934776A CN 114934776 A CN114934776 A CN 114934776A CN 202210592842 A CN202210592842 A CN 202210592842A CN 114934776 A CN114934776 A CN 114934776A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/08—Lining with building materials with preformed concrete slabs
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The application discloses a construction method for inhibiting frost heaving and thaw collapse of water-rich geology, which comprises freezing hole construction, freezing refrigeration system installation, active freezing, excavation construction and grouting, wherein in the freezing hole construction, a designed tunnel is constructed in a subsection mode, working wells are respectively excavated at two ends of each construction section, a freezing pipe is used as a drill rod, a deviation correcting device is installed at the front end of the drill rod, a direction finder is used for guiding and positioning the freezing pipe, a probe of the direction finder is installed in the drill rod and connected with a pull rope, a drilling machine is used for drilling the freezing pipe from one working well to the other working well, the length direction of the freezing pipe is along the direction of the designed tunnel, the inclination angle of the freezing pipe is measured at regular time in the drilling process of the freezing pipe, and the probe of the direction finder is pulled out by the pull rope after the freezing pipe passes through the working well in front of the drilling direction. The method has the effect of reducing the difference of freezing speed of different positions of the freezing curtain of the same circle.
Description
Technical Field
The invention relates to the field of freezing construction, in particular to a construction method for inhibiting frost heaving and thaw collapse of water-rich geology.
Background
Due to complex urban environment and complex hydrogeological conditions, when the tunnel is not suitable for construction by adopting a shield method and a common drainage method, the freezing method is more applied to the water-rich stratum by virtue of the advantages of good water sealing property, high strength of reinforced soil, strong adaptability, good safety and the like. The freezing method is that the water-bearing soil body utilizes a freezing pipe which is manually arranged, a refrigerant agent circulates in the freezing pipe, heat in the soil body is taken away, frozen soil with high strength and good sealing performance is formed, and the effects of bearing load and sealing and waterproofing are achieved. The frozen soil cylinders formed around each freezing pipe have diameters which increase with time, and the cylinders are mutually intersected to form a compact and closed freezing curtain which can bear water and soil pressure and block underground water, and can excavate the stratum under the protection of the freezing curtain.
In the related technology, in the process of excavating the tunnel by adopting a freezing method, freezing holes are drilled from the ground to the excavation area of the tunnel and the periphery of the tunnel, then freezing pipes are introduced into the freezing holes, a brine refrigerant is input to the bottoms of the freezing pipes through a brine trunk pipe, the brine refrigerant flows upwards along the freezing pipes and flows back to a refrigerating unit from pipe orifices of the freezing pipes, but the brine refrigerant exchanges heat with soil bodies around the freezing pipes all the time in the flowing process of the freezing pipes, so that the temperature of the brine refrigerant in the freezing pipes is gradually increased from bottom to top, the freezing rates of different positions of the freezing curtain in the same circle are different, the circle crossing of the freezing curtain is influenced, and frost heaving is not easy to control.
With respect to the related art among the above, the applicant believes that the following drawbacks exist: in the related technology, the freezing speed of different positions of the freezing curtain in the same circle is different, so that the intersection of the freezing curtains is influenced, and the frost heaving is not easy to control.
Disclosure of Invention
In order to reduce the difference of the freezing rates of different positions of the freezing curtain in the same circle, the application provides a construction method for inhibiting frost heaving and thaw collapse of water-rich geology.
The application provides a construction method for inhibiting frost heaving and thaw collapse of water-rich geology, which adopts the following technical scheme:
a construction method for inhibiting frost heaving and thaw collapse of water-rich geology comprises the following steps:
freezing hole construction: the method comprises the following steps of constructing a designed tunnel in sections, respectively excavating working wells at two ends of each construction section, taking a freezing pipe as a drill rod, installing a deviation correcting device at the front end of the drill rod, guiding and positioning the freezing pipe by adopting a direction finder, installing a probe rod of the direction finder in the drill rod and connecting the probe rod with a pull rope, drilling the freezing pipe from one working well to the other working well by adopting a drilling machine, measuring the inclination angle of the freezing pipe at regular time in the drilling process of the freezing pipe along the trend of the designed tunnel, and pulling out the probe rod of the direction finder by adopting the pull rope after the freezing pipe penetrates out of the working well in front of the drilling direction;
and (3) installing a freezing and refrigerating system: a freezing and refrigerating system is arranged at a design position and is connected with a freezing pipe to form a circulating pipeline of a brine refrigerant, and the brine refrigerant of the freezing and refrigerating system flows from one end of the freezing pipe to the other end of the freezing pipe;
active freezing: after the freezing and refrigerating system is installed, the freezing and refrigerating system is started to freeze the area around the designed tunnel to form a freezing curtain;
excavating construction: maintaining and freezing the freezing curtain, excavating a designed tunnel region, constructing a preliminary supporting structure while excavating, laying pressure relief holes in the inner part of the tunnel excavation face, and arranging gate valves at the end parts of the pressure relief holes;
grouting: after the designed depth is excavated and the main structure of the tunnel is completed, the freezing and refrigerating system is stopped, and the freezing pipe is cut off and filled; and drilling the primary supporting structure and the freezing curtain by using a drill bit to form a grouting hole, enabling the grouting hole to penetrate through the freezing curtain, connecting a grouting pipe to the grouting hole, and timely grouting according to the melting rate of the freezing curtain and the settlement condition of a soil body.
By adopting the technical scheme, the freezing pipes extend from one working well to another working well, the length direction of the freezing pipes is along the trend of the designed tunnel, the inclination of the freezing pipes is controlled in the drilling process, the distances between all the parts of the freezing pipes and the designed tunnel are kept to be basically consistent, the distances between all the freezing pipes and the designed tunnel are basically consistent, a brine refrigerant enters the freezing pipes from the same end of the freezing pipes, and in the process of flowing of the brine refrigerant in the freezing pipes, the temperature of the brine refrigerant is reduced along with the heat exchange, however, the temperature of the brine refrigerant in the freezing pipes at different positions of the same circle of freezing curtain can be basically kept consistent, therefore, the difference of the freezing rates of different positions of the same circle of freezing curtain can be reduced, the efficiency of forming a circle by the freezing curtain is higher, the time for actively freezing is shortened, and the frost heaving hazard degree is reduced; in addition, the time for the saline refrigerant to enter the freezing curtain at one end of the freezing pipe is shortened, after the length of the freezing curtain meeting the requirement meets the construction requirement, the saline refrigerant can enter one end of the freezing pipe to excavate the tunnel, and the subsequent freezing curtain is continuously frozen while the tunnel is excavated, so that the construction period is shortened.
Preferably, in the positive freezing process, monitoring the soil body swelling degree above the freezing curtain in real time, and when the swelling rate of the soil body reaches a set upper limit value, performing frost heaving control by suspending the freezing of the freezing pipe at the top; on the premise of maintaining the thickness of the freezing curtain and the average temperature of the freezing curtain, the flow of a brine cooling medium in the freezing pipe is adjusted according to the formation settlement change data, so that frost heaving is reduced; during maintenance and freezing, on the premise of ensuring the safety and effectiveness of the freezing curtain, the upper freezing pipe is intermittently frozen, and is stopped properly to reduce the frost heaving pressure.
By adopting the technical scheme, frost heaving can be effectively controlled by suspending freezing of the freezing pipe at the top, frost heaving is convenient to control, and the frost heaving degree can be effectively controlled by adopting a partial intermittent freezing mode, so that the damage of frost heaving is reduced.
Preferably, in the grouting step, a certain amount of water glass slurry is injected into the grouting hole after each grouting is finished, so that the next grouting is facilitated.
Through adopting above-mentioned technical scheme, the sodium silicate thick liquid setting time is long, and in the slip casting step, some injected holes need slip casting many times, through the injected sodium silicate thick liquid, blocks that the injected hole is condensed, the subsequent slip casting of being convenient for.
Preferably, the primary supporting structure comprises tunnel segments, secondary pipes distributed along the direction of the tunnel are fixed on the outer walls of the tunnel segments, and the secondary pipes on two adjacent tunnel segments in the front-rear direction are mutually butted; the tunnel segment is provided with grouting holes penetrating through the inner wall and the outer wall of the tunnel segment, and after a circle of tunnel segment is mounted, the grouting holes are connected by grouting pipes and slurry is injected into a gap between the tunnel segment and the freezing curtain; then let in the auxiliary tube in toward the secondary pipe, the refrigerating system is frozen in the auxiliary tube connection, and the auxiliary tube is along with the installation of tunnel segment is progressively forward to be extended, and the auxiliary tube will fill the tunnel segment and freeze the mud in the clearance between the curtain and freeze.
Through adopting above-mentioned technical scheme, because the excavation width in tunnel can be greater than the width in the tunnel of design, after the installation tunnel section of jurisdiction, there is bigger clearance between tunnel section of jurisdiction and the freezing curtain, among the correlation technique, the clearance between tunnel section of jurisdiction and the freezing curtain carries out slip casting filling again after tunnel major structure is accomplished, but to the great condition of construction tunnel top atress, the bearing capacity of freezing the curtain can be reduced in the clearance between tunnel section of jurisdiction and the freezing curtain to cause the freezing curtain fracture, cause the soil body to sink and freeze the pipe fracture of freezing in the curtain, the refrigerant leaks and causes the incident. This application is in the tunnel section of jurisdiction installation back of accomplishing the round, in time to the tunnel section of jurisdiction and freeze the clearance injection mud between the curtain, nevertheless because the tunnel section of jurisdiction is not all the installation yet accomplished, the pressure of the mud of injection is very little to do not possess the effect that improves the bearing capacity of freezing the curtain. And this application freezes through setting up the secondary pipe, then through setting up the auxiliary tube and will fill the mud that freezes the clearance between tunnel segment and the freezing curtain for freeze the curtain, the mud of pouring into and tunnel segment and link into an organic whole and strut, thereby improved the bearing capacity of freezing the curtain, it is good to open the reinforcement effect of digging the tunnel. The filling and freezing of this application to the tunnel section of jurisdiction and the clearance of freezing between the curtain are along with the excavation of tunnel gos forward, and in time slip casting and freezing after the tunnel section of jurisdiction of round has been installed at every turn to can reduce the probability of collapsing in tunnel, improve the security that the tunnel was excavated, construction safe and reliable. Adopt the auxiliary tube to freeze the mud that fills the clearance between tunnel segment and the freezing curtain, the auxiliary tube lets in the secondary pipe of being connected with the tunnel segment, keeps away from freezing the pipe to reduce the influence of auxiliary tube to the bulk temperature who freezes the curtain, can reduce the influence of excavation tunnel to the temperature that freezes the curtain in addition.
Preferably, the outer wall of the tunnel segment and one side of the auxiliary pipe facing the tunnel segment are respectively provided with a second heat insulation layer.
Through adopting above-mentioned technical scheme, the second insulating layer can reduce the heat exchange between auxiliary tube and the tunnel of excavation to reduce the heat loss of auxiliary tube and frozen mud, the energy saving.
Preferably, one end of the secondary pipe is provided with a connecting pipe, the other end of the secondary pipe is provided with a connecting hole, the connecting pipe can be sleeved in the connecting hole of the other auxiliary pipe, and the secondary pipe is made of a bendable rubber pipe.
Through adopting above-mentioned technical scheme, through the setting of connecting hole and connecting pipe, make things convenient for the butt joint of secondary pipe, the secondary pipe can be crooked, reduces the condition emergence of the secondary pipe butt joint difficulty that arouses because tunnel segment installation error.
Preferably, freeze refrigerating system and include freezing unit, brine pump, brine tank, feed pipe and return the liquid pipe, freezing unit connection brine pump, the brine pump is connected the brine tank, the brine tank is connected return the one end of liquid pipe, return the other end of liquid pipe and connect freeze the one end of pipe, the other end of freezing the pipe is connected the one end of feed pipe, the other end of feed pipe is connected freezing unit. Every it lets in many to freeze in the pipe the feed pipe, many the feed pipe lets in the degree of depth that freezes the pipe is different, the feed pipe is including freezing section and heat insulation section, it locates to freeze the section the feed pipe lets in the front end of freezing the part of pipe lets in same root freeze many of pipe the section that freezes of feed pipe is in the edge connect gradually on freezing the length direction's of pipe the position, the outer wall of heat insulation section is equipped with first insulating layer.
By adopting the technical scheme, the brine cooling medium introduced into the freezing pipe through the liquid supply pipe exchanges heat with soil around the freezing pipe all the time in the freezing pipe, if only one liquid supply pipe is introduced into one freezing pipe, the temperature of the brine cooling medium is higher along with the flow of the brine cooling medium, the freezing speed of the soil is slower, the freezing speed difference of the soil at different positions is large, the frost heaving degree of the position with the slow freezing speed is larger, the condition of uneven thickness of the freezing curtain can occur, the stability of the freezing curtain is reduced, the finishing time of the freezing curtain is influenced, and a large amount of energy is wasted. This application is through every it lets in many in the pipe to freeze to let in the degree of depth difference the feed pipe can reduce the temperature difference that freezes pipe brine refrigerant everywhere to improve the homogeneity that freezes the soil body around the pipe and freeze, improve the formation quality and the stability of freezing the curtain, reduce the energy waste, reduce the probability of occurrence of the frost heaving destruction of big degree.
Preferably, in freezing the hole construction, drill out a vertical hole that intersects with freezing pipe from ground to the underground at every 30 meters, vertical hole is accomplished before freezing the pipe and arriving the intersection, then use the connecting rod to let in a spacing ring to the intersection, and fix the upper end of connecting rod subaerial, the spacing ring passes through locking mechanism and connects on the connecting rod, locking mechanism is connected with operating handle through the cable, operating handle installs in the upper end of connecting rod, the in-process that freezes the pipe and drills in-process from the inside of spacing ring through, freeze the hole construction and accomplish the back, open locking mechanism through operating handle, make spacing ring and connecting rod separation, then take out the connecting rod.
By adopting the technical scheme, the limit ring limits the freezing pipe, so that the phenomenon that the front end of the freezing pipe is too far away from a drilling machine to shake greatly is avoided, and the drilling precision of the freezing pipe is improved.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the temperature of the brine cooling medium in the freezing pipes at different positions of the same circle of freezing curtain can be basically kept consistent, so that the difference of the freezing speed of different positions of the same circle of freezing curtain can be reduced, the efficiency of forming a circle of the freezing curtain is higher, the positive freezing time is shortened, and the frost heaving hazard degree is reduced.
2. This application is in the tunnel section of jurisdiction installation back of accomplishing the round, in time to the tunnel section of jurisdiction and freeze the clearance injection mud between the curtain, nevertheless because the tunnel section of jurisdiction is not all installation yet accomplished, the pressure of the mud of injection is very little to possess the effect that improves the bearing capacity of freezing the curtain. The slurry filled in the gap between the tunnel segment and the freezing curtain is frozen through the auxiliary pipe, so that the freezing curtain, the injected slurry and the tunnel segment are connected into a whole for supporting, and the bearing capacity of the freezing curtain is improved;
3. this application is through every it lets in many in the pipe to freeze to let in the degree of depth different the feed pipe can reduce the temperature difference that freezes the pipe brine-cooling medium everywhere to make the soil body that freezes around the pipe evenly freeze, improve the formation quality and the stability of freezing the curtain, reduce the emergence of the frost heaving destruction of big degree.
Drawings
Fig. 1 is a flow chart of a construction method for inhibiting frost heaving and thaw collapse in a water-rich geology according to an embodiment of the present application.
Fig. 2 is a schematic view of the installation of the liquid supply tube and the liquid return tube in the second embodiment of the present application.
Fig. 3 is a schematic structural diagram of a tunnel segment according to the second embodiment of the present application.
Description of reference numerals:
1. a freezing pipe; 2. a liquid supply tube; 3. a liquid return pipe; 4. a tunnel segment; 5. and (4) secondary tubes.
Detailed Description
The present application is described in further detail below with reference to figures 1-3.
The embodiment of the application discloses a construction method for inhibiting frost heaving and thawing sinking of water-rich geology.
Example one
Referring to fig. 1, a construction method for inhibiting frost heaving and thaw collapse of a water-rich geology comprises the following steps:
tee joint is one: the municipal administration is connected with tap water, and the wastewater is discharged into a municipal pipe network after being precipitated in a three-stage sedimentation tank. And laying a two-inch galvanized tap water pipeline to a construction working surface for supplying water for subsequent freezing hole drilling. The water receiving pipe is directly connected with the main pipeline and is used for supplying water to the refrigerating station. One-time one-inch half-galvanized welded steel pipe pipeline is laid on a construction site to the ground, two submersible pumps are installed at the sewage discharge position and used for sewage discharge of the construction site, and the water pumps are assigned with special persons on duty every shift to prevent the water pumps from being burnt out. The power consumption of the construction site is accessed from a power supply interface provided by the first party through a low-voltage cable, the power consumption of a freezing station arrangement area arranged in the subsequent construction is large, and the power consumption is accessed from a high-voltage box transformer substation provided by the first party. The construction sites all need to be hardened, and the construction sites meet the requirements of 25t crane access and operation.
And (3) freezing hole construction: and (3) constructing the designed tunnel in sections, leveling the construction ground of the tunnel in sections, respectively excavating a working well at two ends of each construction section, and laying an insulating layer on the drilling operation surface of the working well within a laying range not less than 1m outside the boundary of the design freezing curtain. The heat insulating layer is made of flame-retardant flexible plastic foam board, has a thermal conductivity not greater than 0.04W/m.h, has a water absorption not greater than 2%, and can not be soaked in water. The thickness of the heat-insulating layer is not less than 40mm, and the thickness of the heat-insulating layer is not less than 60mm during construction for 5-10 months. When the heat insulation plates are adopted, the heat insulation plates are sealed and attached to the side wall of the working well by adopting special glue, and no gap is formed between the plates. A lifting platform is built in one of the working wells, a chain block is mounted on the upper portion of the lifting platform, and the position of the drilling machine is adjusted through the chain block and the lifting platform. Adopting a phi 168 drill bit to open a hole on the side wall of the working well for one time, wherein the opening depth is 360mm, an orifice pipe with the outer diameter phi 168 x 5 is arranged at the orifice, and the outer end of the orifice pipe is provided with a ball valve. And (3) adopting a phi 150 drill bit to penetrate into the orifice pipe for secondary hole opening, enabling the drill bit to penetrate through the side wall of the working well, then pumping out the drill bit, closing the ball valve and preventing silt from flowing in. The freezing pipes are used as drill rods, a drilling machine is adopted to drill and lay the freezing pipes around the designed tunnel along the direction of the designed tunnel, efficient wall protection slurry is adopted to circulate in the drilling process, two ends of each freezing pipe are respectively communicated with working wells at two ends of the construction section, then the construction of one freezing hole is completed, and then the drilling machine is moved to continue the construction of the next drilling hole. The front end of the drill rod is provided with a deviation correcting device which is a 20-degree duck-leg drill bit. The freezing pipe is guided and positioned by adopting the direction finder, the probe rod of the direction finder is arranged in a drill rod and connected with a pull rope, the freezing pipe is drilled from one working well to the other working well by adopting a drilling machine, the length direction of the freezing pipe is along the trend of a designed tunnel, the inclination angle of the freezing pipe is measured by adopting a gyro inclinometer at regular time in the drilling process of the freezing pipe, and the probe rod of the direction finder is pulled out by adopting the pull rope after the freezing pipe penetrates out from the working well in front of the drilling direction. In the drilling process, the drilling deflection is controlled according to 0.5m, a direction finder is adopted for orientation every ten meters, the inclination angle of the freezing pipe is measured through a gyro inclinometer, and the deviation rectification treatment is carried out when the deflection exceeds twenty centimeters, so that the trend of the freezing pipe is consistent with the trend of the tunnel. And (4) re-drilling the hole with larger deflection to ensure that the maximum deflection of the final hole is not larger than the design requirement, adopting lamplight or a horizontal gyro for inclination measurement, if the maximum deflection exceeds the design allowable range, prompting the design to confirm the distance between the final holes, and supplementing the frozen holes if necessary. After the freezing pipe is drilled, a freezing pipe pressure-resistant test is required, the test pressure is twice of the salt water pressure of the freezing working surface, the test pressure is not lower than 0.80MPa, the pressure is not higher than 0.05MPa after the pressure is tested for 30min, and the pressure is maintained to be qualified after the pressure is continued for 15 min.
And (3) installing a freezing and refrigerating system: and the freezing and refrigerating systems are respectively arranged around the two working wells and are connected with the freezing pipes to form a circulating pipeline of a brine refrigerant, and the brine refrigerant of the freezing and refrigerating system flows from one end of the freezing pipe to the other end of the freezing pipe. After the freezing and refrigerating system is installed, trial operation is carried out, whether a leakage place exists is checked, and if the leakage exists, the leakage is repaired in time.
Active freezing: after the freezing and refrigerating system is in test operation, the freezing and refrigerating system is started, the area around the designed tunnel is frozen to form a freezing curtain, and the temperature of the freezing curtain is monitored. The active freezing time reaches the design requirement, the brine temperature reaches the design minimum brine temperature of-28 ℃, the temperature difference of a brine return circuit is not more than 2 ℃, and when the thickness of the frozen soil wall and the average temperature reach the design requirement, the excavation construction can be carried out.
Excavating construction: and (3) maintaining and freezing the freezing curtain, monitoring the freezing curtain as in the positive freezing process during the maintenance of the freezing curtain, ensuring that the freezing refrigeration system operates normally, and analyzing the temperature change of the freezing curtain in time. And then excavating the designed tunnel area, constructing a preliminary supporting structure while excavating, laying pressure relief holes in the inner part of the tunnel excavation face, and arranging gate valves at the end parts of the pressure relief holes. In the excavation process, the surface temperature and the displacement of the exposed freezing curtain are monitored every day, and if the temperature of the local freezing curtain is higher and the deformation is larger, the flow of the freezing pipe at the corresponding position can be increased by a method of connecting pipeline pumps in series.
Grouting: and after the designed depth is excavated and the main structure of the tunnel is completed, stopping the freezing and refrigerating system, cutting off and filling the freezing pipe, wherein the cutting-off depth of the freezing pipe is not less than 60mm when the freezing pipe enters the structural surface of the working well, completely blowing a salt water cooling medium in the freezing pipe by using compressed air before filling the freezing pipe, filling by using cement mortar above M10 or micro-expansion concrete above C20, wherein the filling length of the freezing pipe at the upper elevation angle is not less than 1.5M in the pipe orifice, and filling the freezing pipe at the lower elevation angle in a full section. And drilling the primary supporting structure and the freezing curtain by adopting a drill to form a grouting hole, wherein the grouting hole penetrates through the freezing curtain, and the grouting amount and the grouting time interval are adjusted in time according to the monitoring of ground deformation and a thawing temperature field to ensure the stability of settlement. And then connecting the grouting pipe to the grouting hole, and timely grouting according to the melting rate of the freezing curtain and the settlement condition of the soil body.
In the positive freezing process, monitoring the soil body swelling degree above the freezing curtain in real time, and when the swelling rate of the soil body reaches a set upper limit value, performing frost heaving control by suspending the freezing of the freezing pipe at the top; on the premise of maintaining the thickness of the freezing curtain and the average temperature of the freezing curtain, the flow of a brine cooling medium in the freezing pipe is adjusted according to the formation settlement change data, so that frost heaving is reduced; during maintenance freezing, on the premise of ensuring the safety and effectiveness of the freezing curtain, the upper freezing pipe is frozen in a clearance manner, and is stopped properly, so that the frost heaving pressure is reduced.
The brine refrigerant configuration method comprises the following steps: firstly, the clean water of about 1/4 is injected into the brine tank, then the pump is started to circulate and solid calcium chloride is gradually added until the brine concentration reaches the design requirement, and impurities are removed when the calcium chloride is dissolved. The brine tank cannot be filled too full to prevent the brine from overflowing when the brine flows back through the freezing pipe above the opening of the brine tank.
In the grouting step, a certain amount of water glass slurry is injected into the grouting hole after each grouting is finished, so that the next grouting is facilitated.
The implementation principle of the construction method for inhibiting frost heaving and thaw collapse of the water-rich geology in the embodiment of the application is as follows: the freezing pipes extend from one working well to the other working well, the length direction of the freezing pipes is along the direction of a designed tunnel, the inclination of the freezing pipes is controlled in the drilling process, the distances between all the parts of the freezing pipes and the designed tunnel are basically consistent, the distances between all the freezing pipes and the designed tunnel are basically consistent, a brine refrigerant enters the freezing pipes from the same end of the freezing pipes, the temperature of the brine refrigerant is reduced along with the proceeding of heat exchange in the process that the brine refrigerant flows in the freezing pipes, however, the temperature of the brine refrigerant in the freezing pipes at different positions of the same circle of freezing curtain can be basically consistent, so that the difference of the freezing rates of different positions of the same circle of freezing curtain can be reduced, the efficiency of forming a circle of the freezing curtain is higher, the time of active freezing is shortened, and the degree of frost damage is reduced; in addition, the time for the saline refrigerant to enter the freezing curtain at one end of the freezing pipe is shortened, after the length of the freezing curtain meeting the requirement meets the construction requirement, the tunnel can be excavated from one end of the saline refrigerant entering the freezing pipe, and the subsequent freezing curtain is continuously frozen while the tunnel is excavated, so that the construction period is shortened.
Example two
Referring to fig. 2, the difference between the second embodiment and the first embodiment is that the freezing and refrigerating system includes a freezing unit, a brine pump, a brine tank, a liquid supply pipe 2 and a liquid return pipe 3, the freezing unit is connected to the brine pump, and an evaporator and a low-temperature pipeline of the freezing unit are wrapped by flexible foam for heat preservation. The brine tank is connected to the brine pump, and the brine tank is connected back the one end of liquid pipe 3, and the one end of freezing pipe 1 is connected to the other end of returning liquid pipe 3, and the other end of freezing pipe lets in the one end of feed pipe 2, and the refrigeration unit is connected to the other end of feed pipe 2, and the one end that freezes pipe 1 and lets in feed pipe 2 is equipped with the orificial plug of shutoff. The brine tank, the part of the liquid supply pipe 2 arranged outside the freezing pipe 1 and the liquid return pipe 3 are respectively wrapped by polystyrene foam plates with the thickness of 50mm for heat preservation. Temperature, pressure and flow monitoring devices are laid on the liquid supply pipe 2 and the liquid return pipe 3. A plurality of liquid supply pipes 2 are respectively led into each freezing pipe 1, the liquid supply pipes 2 are respectively led into the freezing pipes 1 from ports at two ends of the freezing pipes and intersect at the middle positions of the freezing pipes 1, and the depth of each liquid supply pipe 2 led into the freezing pipes 1 is different. The liquid supply pipe 2 comprises a freezing section and a heat insulation section, the freezing section is arranged at the front end of the part of the liquid supply pipe 2 which is communicated with the freezing pipe 1, the freezing sections of the liquid supply pipes 2 which are communicated with the same freezing pipe 1 are sequentially connected at the positions along the length direction of the freezing pipe 1, and the outer wall of the heat insulation section is provided with a first heat insulation layer which is made of composite silicate heat insulation paint. A plurality of liquid supply pipes 2 with different introduction depths are introduced into each freezing pipe 1, and the temperature difference of the brine medium at each position of the freezing pipe 1 can be reduced by controlling the flow of each liquid supply pipe 2, so that soil bodies at each position in the length direction of the freezing pipe 1 are uniformly frozen, the forming quality and stability of the freezing curtain are improved, and the forming time of the freezing curtain is further shortened.
Referring to fig. 3, in another embodiment, the preliminary supporting structure includes a tunnel segment 4, a secondary pipe 5 arranged along the trend of the tunnel is fixed on the outer wall of the tunnel segment 4, one end of the secondary pipe 5 is provided with a connecting pipe, the other end of the secondary pipe 5 is provided with a connecting hole, the connecting pipe can be sleeved in the connecting hole of another auxiliary pipe, the secondary pipe 5 is made of a rubber pipe which can be bent, the connecting pipes of the secondary pipes 5 on two adjacent tunnel segments 4 in the front-rear direction are connected with the connecting holes, the outer wall of the tunnel segment 4 and one side of the auxiliary pipe facing the tunnel segment 4 are respectively provided with a second thermal insulation layer, and the second thermal insulation layer is made of composite silicate thermal insulation paint. Be equipped with the slip casting hole that runs through the inner wall and the outer wall of tunnel segment 4 on tunnel segment 4, the rear portion of tunnel segment 4 is located to the slip casting hole, accomplishes the tunnel segment 4 installation back of round, adopts slip casting union coupling slip casting hole and toward tunnel segment 4 and freeze the clearance injection mud between the curtain, and mud is from the front end of tunnel segment 4 overflow and go out to stop the slip casting promptly. Then let in the auxiliary tube in toward secondary pipe 5, the auxiliary tube can realize the salt solution refrigerant self-loopa, and the salt solution refrigerant does not flow to in the secondary pipe 5, and the access way of secondary pipe 5's effect for providing the auxiliary tube, auxiliary tube connects freezes refrigerating system, and the auxiliary tube is along with tunnel section of jurisdiction 4's installation forward extension gradually, and the auxiliary tube will be filled tunnel section of jurisdiction 4 and freeze the mud in the clearance between the curtain and freeze. Every completion round tunnel segment 4 and freeze the slip casting between the curtain with freeze the back, resume the installation of the tunnel segment 4 of next round again, before the installation of next round tunnel segment 4, the mud that spills over of the front end of the tunnel segment 4 of round in the clearance, the mud of avoiding spilling over influences the installation of tunnel segment 4. And constructing a two-lining structure at the position of the tunnel segment 4 subjected to the slurry freezing, wherein the two-lining structure avoids the grouting hole. After the tunnel segment 4 of one circle is installed, slurry is injected into a gap between the tunnel segment 4 and the freezing curtain in time, and then the slurry filled into the gap between the tunnel segment 4 and the freezing curtain is frozen through the auxiliary pipe, so that the freezing curtain, the injected slurry and the tunnel segment 4 are connected into a whole for supporting, and the bearing capacity of the freezing curtain is improved.
In another embodiment, a vertical hole which is intersected with a drill rod is drilled from the ground to the underground every 30 meters, the vertical hole is completed before the freezing pipe 1 reaches the intersection, then a limiting ring is led into the intersection by using a connecting rod, the connecting rod is fixed on the ground in a ground nail or concrete pouring mode, the freezing pipe 1 passes through the limiting ring, the limiting ring limits the freezing pipe 1, the freezing pipe 1 is prevented from shaking greatly due to the fact that the freezing pipe 1 is far away from a drilling machine, and the drilling precision of the freezing pipe 1 is improved.
Drilling a vertical hole which is intersected with the freezing pipe 1 from the ground to the underground every 30 meters, completing the vertical hole before the freezing pipe 1 reaches the intersection, then using a connecting rod to lead a limiting ring to the intersection, and fixing the upper end of the connecting rod to the ground. The spacing ring is connected on the connecting rod through locking mechanism, and locking mechanism is connected with operating handle through the cable, and operating handle installs in the upper end of connecting rod, and locking mechanism is the mechanical lock, and on locking mechanism's hasp was fixed in the spacing ring, locking mechanism's lock core was fixed in the lower extreme of connecting rod, and the lock core dies through the bolt lock with the hasp, and the bolt connection cable can be to the unblock of locking mechanism through stay cord control bolt. The freezing pipe 1 passes through the inside of spacing ring in the process of drilling, after freezing hole construction, through operating handle and stay cord control locking mechanism unblock for spacing ring and connecting rod separation, then take out the connecting rod. The limit ring limits the freezing pipe 1, so that the phenomenon that the front end of the freezing pipe 1 is too far away from a drilling machine to cause large-amplitude shaking is avoided, and the drilling precision of the freezing pipe 1 is improved.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (8)
1. A construction method for inhibiting frost heaving and thaw collapse of water-rich geology is characterized by comprising the following steps: the method comprises the following steps:
and (3) freezing hole construction: the method comprises the following steps of constructing a designed tunnel in sections, respectively excavating working wells at two ends of each construction section, taking a freezing pipe as a drill rod, installing a deviation correcting device at the front end of the drill rod, guiding and positioning the freezing pipe by adopting a direction finder, installing a probe rod of the direction finder in the drill rod and connecting the probe rod with a pull rope, drilling the freezing pipe from one working well to the other working well by adopting a drilling machine, measuring the inclination angle of the freezing pipe at regular time in the drilling process of the freezing pipe along the trend of the designed tunnel, and pulling out the probe rod of the direction finder by adopting the pull rope after the freezing pipe penetrates out of the working well in front of the drilling direction;
and (3) installing a freezing and refrigerating system: a freezing refrigeration system is arranged at a design position and is connected with a freezing pipe to form a circulation pipeline of a brine refrigerant, and the brine refrigerant of the freezing refrigeration system flows from one end of the freezing pipe to the other end of the freezing pipe;
active freezing: after the freezing and refrigerating system is installed, the freezing and refrigerating system is started to freeze the area around the designed tunnel to form a freezing curtain;
excavating construction: maintaining and freezing the freezing curtain, excavating a designed tunnel region, constructing a preliminary supporting structure while excavating, and arranging pressure relief holes in the inner part of the tunnel excavation surface, wherein the end parts of the pressure relief holes are provided with gate valves;
grouting: after the designed depth is excavated and the main structure of the tunnel is completed, the freezing and refrigerating system is stopped, and the freezing pipe is cut off and filled; and drilling the primary supporting structure and the freezing curtain by adopting a drill to form a grouting hole, enabling the grouting hole to penetrate through the freezing curtain, connecting a grouting pipe to the grouting hole, and timely grouting according to the melting rate of the freezing curtain and the settlement condition of a soil body.
2. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 1, characterized in that: in the positive freezing process, monitoring the soil body swelling degree above the freezing curtain in real time, and when the swelling rate of the soil body reaches a set upper limit value, performing frost heaving control by suspending the freezing of the freezing hole at the top; on the premise of maintaining the thickness of the freezing curtain and the average temperature of the freezing curtain, the flow of a brine cooling medium in the freezing pipe is adjusted according to the formation settlement change data, so that frost heaving is reduced; during maintenance and freezing, on the premise of ensuring the safety and effectiveness of the freezing curtain, the upper freezing pipe is intermittently frozen, and is stopped properly to reduce the frost heaving pressure.
3. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 1, characterized in that: in the grouting step, a certain amount of water glass slurry is injected into the grouting hole after each grouting is finished, so that the next grouting is facilitated.
4. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology as claimed in claim 1, wherein the construction method comprises the following steps: the primary supporting structure comprises tunnel segments, secondary pipes distributed along the direction of a tunnel are fixed on the outer walls of the tunnel segments, and the secondary pipes on two adjacent tunnel segments in the front-rear direction are mutually butted; the tunnel segment is provided with grouting holes penetrating through the inner wall and the outer wall of the tunnel segment, and after a circle of tunnel segment is mounted, the grouting holes are connected by grouting pipes and slurry is injected into a gap between the tunnel segment and the freezing curtain; then let in the auxiliary tube in toward the secondary pipe, the refrigerating system is frozen in the auxiliary tube connection, and the auxiliary tube is along with the installation of tunnel segment is progressively forward to be extended, and the auxiliary tube will fill the tunnel segment and freeze the mud in the clearance between the curtain and freeze.
5. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 4, characterized in that: and a second heat insulation layer is respectively arranged on the outer wall of the tunnel segment and one side of the auxiliary pipe, which faces the tunnel segment.
6. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 4, characterized in that: one end of the secondary pipe is provided with a connecting pipe, the other end of the secondary pipe is provided with a connecting hole, the connecting pipe can be sleeved into the connecting hole of the other auxiliary pipe, and the secondary pipe is made of a bendable rubber pipe.
7. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 1, characterized in that: the freezing and refrigerating system comprises a freezing unit, a brine pump, a brine tank, a liquid supply pipe and a liquid return pipe, the refrigerating unit is connected with a brine pump, the brine pump is connected with the brine tank, the brine tank is connected with one end of the liquid return pipe, the other end of the liquid return pipe is connected with one end of the freezing pipe, the other end of the freezing pipe is connected with one end of the liquid supply pipe, the other end of the liquid supply pipe is connected with the refrigerating unit, a plurality of liquid supply pipes are introduced into each freezing pipe, the depths of the liquid supply pipes introduced into the freezing pipes are different, the freezing section is arranged at the front end of the part, communicated with the freezing pipe, of the liquid supply pipe, the freezing sections communicated with the freezing pipe are sequentially connected at the positions along the length direction of the freezing pipe, and a first heat insulation layer is arranged on the outer wall of the heat insulation section.
8. The construction method for inhibiting frost heaving and thaw collapse of the water-rich geology according to claim 1, characterized in that: in freezing the hole construction, drill out one from ground toward the underground at every 30 meters and freeze the vertical hole that the pipe intersects, vertical hole is accomplished before freezing the pipe and reacing the intersection, then use the connecting rod to let in a spacing ring to the intersection, and fix the upper end of connecting rod subaerial, the spacing ring passes through locking mechanism and connects on the connecting rod, locking mechanism is connected with operating handle through the cable, operating handle installs in the upper end of connecting rod, the in-process that freezes the pipe and drills into passes through from the inside of spacing ring, freeze the hole construction and accomplish the back, open locking mechanism through operating handle, make spacing ring and connecting rod separation, then take out the connecting rod.
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| CN104963334A (en) * | 2015-07-13 | 2015-10-07 | 南京林业大学 | Construction method for utilizing grouting freezing pipe to reinforce and freeze contact passage to restrain frost heaving and thaw collapsing |
| JP2016011550A (en) * | 2014-06-30 | 2016-01-21 | 清水建設株式会社 | Tunnel construction method |
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| CN101463724A (en) * | 2008-12-30 | 2009-06-24 | 上海隧道工程股份有限公司 | Construction method for connection passage by double-row hole horizontal freezing method |
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