Study on the Design of Water Treatment Scheme
for Expressway Tunnel in a Mountainous Area
Xuejian Zhua1*, Nian Zhangb2, Xiaohui Haoc1 and Zepeng Liuc1
1Graduate student of Transportation Engineering, Taiyuan University of Science and Technology, China
2School of Transportation and Logistics, Taiyuan University of Science and Technology, China
Submission: July 09, 2019; Published: July 26, 2019
*Corresponding Author: Xuejian Zhua, Graduate student of Transportation Engineering, Taiyuan University of Science and Technology, Taiyuan city, China
How to cite this article: Xuejian Zhua, Nian Zhangb, Xiaohui Haoc, Zepeng Liuc. Study on the Design of Water Treatment Scheme for Expressway Tunnel in a Mountainous Area. Civil Eng Res J. 2019; 8(5): 555749. DOI: 10.19080/CERJ.2019.08.555749
In the process of tunnel construction in karst area, unexpected geological disasters such as water inrush and mud inrush are often encountered, which brings great disaster and incalculable economic loss to the construction safety, in order to ensure the smooth operation of tunnel construction and the safety of the late construction of the tunnel, it is necessary to select and remove the reasonable construction plan. In the course of highway tunnel construction in a mountainous area, after entering the rainy season, with the tunnel digging into the melting section of the Xeon Rock, the tunnel water inrush and seepage are obviously aggravated, and after the natural drainage of the original design is serious, the reason of the water accumulation in the hole is analyzed, three kinds of water treatment schemes in the hole are formulated, The best treatment scheme was eventually selected. It provides reference for similar karst groundwater treatment and tunnel construction scheme design.
Karst distribution in China is very extensive, accounting for about 1/3 of the land area, karst phenomenon throughout a number of provinces, autonomous regions, municipalities, especially in the southwest Region . With the rapid development of hydropower construction in China, with the introduction and implementation of the National Strategy for the development of the western region, tunnel construction plays an important role in the transportation system, and tunnel inrush water is the most prominent geological disaster in the process of tunnel construction. In the tunnel construction often encounter water inrush, gushing mud and other geological disasters, seriously affect the construction safety, the tunnel construction and operation is also extremely unfavorable . Based on the concrete project case, this paper introduces the comparison between the drainage method of water accumulation problem and the application problem of hydraulic control method in the construction of tunnel under karst geological conditions [3,4], and the best governance plan was selected in the context of various factors.
The tunnel is located in Liupanshui, Guizhou Province, and the route crosses the middle and Low mountain Watershed zone between Yuexi and Jinggou; The tunnel is separated from the
double line, the left-line tunnel is length 3772m, the right-line tunnel length 3800m, is the extralong tunnel; The tunnel profile adopts unidirectional slope, the tunnel route area is located in the subtropical monsoon humid climate ,the climate is pleasant, the tunnel is built in the lava area wiring, the bad geology in the area is mainly karst, in the range of seasonal variation zone of the main body of the tunnel hole, the underground karst is extremely developed, the infiltration condition is good, the groundwater runoff path is short, the water inrush in the rainy season is large, the surface dissolution depression, the funnel and so Gravel and other substances, the rainy season is a surface water collection area.
Tunnel from the beginning of construction, the early construction of the tunnel is relatively normal, the total water inrush in the exit section is generally around 2500 m3/d, the import section using natural smooth slope drainage, water inrush under normal circumstances 1200 m3/d (estimate). Since entering the rainy season, with the excavation of the tunnel outlet section into the melting section of the Xeon Rock, the tunnel water inrush, seepage significantly intensified, water inrush gathered in the vicinity of the tunnel palm, resulting in the cavern was submerged, construction blocked. In order to better solve the problem of tunnel water accumulation, supplement the special hydrogeological survey work, use comprehensive survey means to further explore the hydrogeological and engineering
geology of the tunnel, and provide more detailed hydrogeological
basis for the treatment of karst groundwater and the tunnel
The effluent point of karst fractured water in tunnel is mainly
concentrated in the effluent from the exposed karst pipeline
effluent and the karst fractured water concentrated effluent
passage. The dissolving cavity has a certain discharge capacity,
according to the existing several heavy rainfall tunnel water
accumulation situation found that the original karst pipeline
has a good discharge capacity [5-7], but with the pipeline
construction water and tunnel water discharge, karst pipeline
discharge capacity has been greatly affected, or even blocked, in
the case of heavy rainfall, The occurrence of groundwater reflux
into the tunnel in the Karst pipeline. In the concentrated effluent
section of karst fractured water, the lower seepage of karst
fractured water in this section is slow, and the groundwater in
the area after heavy rainfall is a short and sharp increase, and the
original design uses encrypted annular and transverse drainage
measures to reduce the head pressure behind the lining in order
to ensure the safety of the tunnel structure, However, judging
from the cracking of seepage in lining after several recent heavy
rainfall, the groundwater diversion measures behind the lining
are not very effective. A summary analysis of the main causes of
water accumulation in the hole:
i. The drainage capacity of the dissolving cavity drain
channel is insufficient, and the construction drainage causes
the dissolving cavity blockage;
ii. In the case of heavy rainfall, groundwater infiltration is
too large to exceed drainage capacity
iii. The discharge capacity of karst fractured underwater
seepage channel is low, and the groundwater level rises
sharply under the condition of heavy rainfall.
Due to the construction of a large number of tunnels in
karst area, tunnel workers have mastered some construction
treatment techniques and successful experiences in karst
areas. Junhua Zai  Quansan expressway Sanyang tunnel
large inrush water treatment, put forward the combination
of plugging, plugging mainly treatment measures; Lihui Nan
 It is suggested that when seasonal rainfall is strong, when
the effect of grouting water plugging is not particularly good,
then the drainage pressure is used to drain and buck, and
when the displacement of the spillway hole does not meet the
requirements, the drainage capacity can be improved by adding
transverse drainage channel and drain hole; Qiangqiang Cheng
 A reinforcement technique of top-down segmented grouting
is used to deal with water inrush in a large team through waterwaterrich
karst strata. The monitoring results show that the grouting
reinforcement technique has good effect, overcomes the defect
of repeated sweep hole greatly improves the construction
efficiency, and saves the construction time; Xiaocheng Liu 
An analysis of the present situation of groundwater treatment
research in tunnel construction the paper puts forward that
“plugging combination” is the basic method to control the
groundwater problem in tunnel construction; Zhenhua Fang
In the study of the disease of Karst pipeline inrush in the
Alpine Tunnel on the Chenggui Railway, an additional spillway
hole scheme was proposed to rectify the water inrush disease;
Jing Li, et al.  The large karst water inrush disease appearing
in the Guanhuchong Tunnel is designed for how to deal with the
large amount of water inrush in the cavern safely and effectively;
Xinguo Du  In the process of karst water treatment in
Makoupai tunnel, the dynamic optimization design is carried out,
and the final control construction scheme is obtained. Roughly
divided into two aspects, one is to deal with Karst, the other is to
adjust the tunnel Construction methods ; the treatment of inrush
water, follow the “sparse mainly, plug and discharge combination,
local conditions, comprehensive management” principle, as far
as possible not to change the seepage path of water, according
to the actual situation to choose to Drainage or blocking mainly,
At the same time, consideration should be given to the minimum
impact of the measures taken on the hydrogeological conditions
and surrounding environment of the tunnel . The design of the
treatment scheme of karst water is mainly considered from two
aspects of tunnel drainage capacity problem and tunnel structure
safety, on the one hand, the discharge of groundwater under
the condition of heavy rainfall. The existing tunnel drainage
system cannot fully meet the requirements of karst fractured
water discharge after considering the pipe trench siltation and
other factors, so there are two kinds of schemes to increase
drainage capacity and reduce karst fractured water discharge
in the treatment scheme. On the other hand, the safety problem
of tunnel structure is divided into the safety of tunnel lining
structure and the stability of tunnel base. In view of the above
situation, the treatment measures of are worked out: Based on
the above analysis, three treatment schemes are proposed.
Drainage inside the tunnel, the tunnel on both sides of the
road to add drainage dark Ditch, the cavern reserved Cable
trench Drainage pipe interface, left and right hole center ditch
co-deployment drainage, karst fracture section lining foot added
transverse guide water pipe. According to hydrogeological
data, the maximum effluent capacity of tunnel single hole is
98420m3/d, and the total drainage capacity of the inner drainage
scheme is estimated, in which the left and right hole coordinated
drainage is calculated according to 15000m3/d, and the total
drainage capacity of the cavern drainage scheme considering
siltation and other unfavorable factors is about 166939m3/d,
drainage capacity is 1.7times the forecast water inrush. The residual coefficient of drainage capacity corresponding to the
remaining displacement of the right hole is 1.92, the surplus
coefficient of drainage capacity of two holes is higher, and the
drainage safety is more abundant. In terms of structural safety, a
transverse water guide with a longitudinal spacing of 5m and a
length of 4m is set up in the paragraph of Karst fractured water
development, which can effectively reduce the underwater
pressure behind the lining, and according to the existing design
data Figure 1, the lining is guaranteed when the structure safety
is not more than 15m (design elevation ) under the action of
Grouting water plugging, rock-soluble fracture section lining
behind the surrounding rock grouting water plugging. Grouting
water plugging, through the surrounding rock grouting water
plugging to reduce the amount of groundwater discharged into
the tunnel. Because the data of karst fractured water effluent
is not accurately obtained, it is estimated that the water inrush
when the palmar surface is revealed during the construction
process, according to the construction data, when the karst is
exposed, the tunnel is flooded for about 200m, and the water
is converted to 3360m3, according to 3 times the magnification
is considered to obtain the water output is 10080m3/d, then
the drainage capacity after plugging is 1.07 times , the drainage
surplus capacity is small. In terms of structural safety, after grouting water plugging, the discharge of groundwater in the
mountain is reduced, the water level in the interior of the rock
mass will be higher, and the water pressure in the block has a
great influence on the safety of two lining structures, Figure
2 resulting in local structural damage and leakage, In general,
the safety of the structure is guaranteed by using the reinforced
anti-hydraulic lining structure in the fully enclosed lining design
of grouting water plugging.
The comparison of the scheme is mainly considered from
the aspects of drainage capacity, structural safety, technical
difficulty, construction risk, duration and project cost, in order
to select the relative optimal scheme.
Advantages: Drainage system are located in the tunnel,
construction management and quality control is simple,
construction technology difficulty and construction risk are low.
a. The maintenance requirements of the drainage system
in the tunnel are high, the central ditch in the tunnel, the
drainage dark ditch on both sides of the roadbed and the
contact channel between them are prone to siltation or even
blockage, which will reduce the drainage capacity of the
tunnel and have a great influence on the safety of the tunnel
structure, so the regular maintenance requirements of the
drainage system are high.
b. On both sides of the road drainage dark ditch cover into
the road lane about 10cm, although the longitudinal length
of 10m of a longer plate cover to improve the stability of the
cover plate, but the slow lane heavy vehicle driving process
will still have a certain impact on the road surface, when the
cover plate and dark ditch side wall construction quality
control is poor, The operation stage is easy to cause local
damage of pavement.
c. It is necessary to carry out large section of pavement
concrete side ditch excavation and part of the bottom backfill
layer to break the construction, the construction efficiency is
low, the main hole excavation has a certain interference.
d. When there are extreme conditions such as siltation
and blockage of drainage system, the amount of short-term
heavy rainfall may cause the water inrush in the hole to be
discharged in time, and the road surface will be damaged by
Advantages: Radial grouting consolidation can effectively
improve the surrounding rock, and the formation of waterstopping
ring can reduce the influence of groundwater on
the stress of tunnel structure to a certain extent; The cost of
treatment is relatively low.
I. Grouting Sealing construction technology is more
difficult, plugging effect and construction level is closely
related, it is necessary to have a wealth of grouting
construction experience team to ensure the construction
quality, and karst pipeline water plugging is difficult, easy
to form a high pressure in the local situation, the two-lining
structure of the force has a greater safety hazard.
II. The grouting holes formed by punching grouting on
the two lining have been destroyed, which can destroy the
lining structure and waterproof plate, and easily form local
III. Treatment paragraph two lining has been completed,
two-lining drilling grouting affects the appearance of quality,
the tunnel quality assessment has a certain impact.
IV. After plugging, the remaining passages still have karst
fissure water pouring into the tunnel, the reduction of water
inrush in the tunnel after plugging is not obvious, and the
surplus degree of drainage safety is not easy to be evaluated.
According to the above discussion and comparison, the
treatment effect of the scheme II is uncertain, the drainage
surplus coefficient is low. The scheme I is designed with the
maximum projected water consumption in the tunnel of 98000
m3/d, the data are estimated on the basis of 6 hours of rainfall
during construction, the design basis is sufficient, the design
drainage capacity is 1.7 times the maximum projected water
inrush, the surplus is higher, the reliability is better, Although
the scheme has some interference to the main hole excavation
construction, the side gutter cover into the lane 10cm may cause
the pavement to be partially damaged in the operation process,
the drainage system maintenance requirements are high, but the
design basis of the scheme is adequate, the drainage surplus is
appropriate Table 1, the structure safety is high, the construction
period basically meets the requirements, the cost is relatively
lower, Therefore, it is recommended to adopt the scheme I as the
treatment scheme of karst water in this tunnel.
The selection of construction schemes in engineering
construction is particularly important. A scientific and rational
construction plan will not only improve the economic benefits of
project management, but also have a huge impact on the social
benefits of the project. When selecting a construction plan, it is
required to do a comprehensive comparison and comprehensive
consideration of the actual situation of the combined project,
and to find an optimal solution that can solve the engineering
problem and save the engineering cost. This paper first analyzes
the specific causes of water accumulation in the cave, gives a
variety of treatment options, introduces the advantages and
disadvantages of the treatment schemes in the water treatment
in the tunnel and the matters that should be paid attention
to during the comparison and selection process. The good
governance program provides reference for tunnel engineering
design, construction and comprehensive rectification work of
This work is sponsored by the Found of Institute of Highway
Science, Ministry of Transport (201733) and the Youth Fund
of Taiyuan University of Science and Technology (20153014)
which are gratefully acknowledged.
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