EP3599343A1

EP3599343A1 - Design method and system for active control type waterproof and drainage system of subsea tunnel

Info

Publication number: EP3599343A1
Application number: EP19188578.9A
Authority: EP
Inventors: Dingli ZHANG; Zhenyu Sun
Original assignee: Beijing Jiaotong University
Current assignee: Beijing Jiaotong University
Priority date: 2018-07-27
Filing date: 2019-07-26
Publication date: 2020-01-29
Also published as: CN109026144B; CN109026144A

Abstract

The present invention discloses a design method and system for an active control type waterproof and drainage system of a subsea tunnel. The method includes: acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel (101); determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel (102); determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel (103), and if yes, acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures (104); and, determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads (105). The design method and system provided by the present invention can reduce the subjectivity of the waterproof and drainage design of the subsea tunnel and improve the scientificity thereof, and at the same time, avoid waste, and eliminate safety hazards in tunnel construction due to unreasonable design.

Description

TECHNICAL FIELD

The present invention relates to the field of subsea tunnel drainage, and in particular, to a design method and system for an active control type waterproof and drainage system of a subsea tunnel.

BACKGROUND

Subsea tunnels are buried under a seabed, and are replenished with an inexhaustible water source. However, due to the limitation of a V-shaped longitudinal slope, they cannot achieve natural drainage, but merely rely on artificial drainage. The subsea tunnels bear a large water head, and the water load acts on support structures is often large. Therefore, the rationality of waterproof and drainage design determines the safety of the support structures and the drainage cost during operation.
In tunnel engineering at home and abroad, the commonly used water waterproof and drainage methods can be divided into two types: fully enclosed and drained. In a fully enclosed waterproof tunnel, the support structures are subjected to an external water pressure which is basically equivalent to the underground water head; when a drained waterproof method is adopted, the external water pressure acting on the support structures and the probability of deterioration and leakage both can be reduced, but it is necessary to control the drainage capacity of groundwater and prevent blockage of the drainage system. Although the design principle of "blocking water and limiting drainage" has been proposed in the present subsea tunnels, only the water blocking effect of a secondary lining structure is often considered; as a result, the secondary lining is often too conservatively designed when the water pressure is too large, or is thinly designed to cause unaffordable drainage costs during operation.
Therefore, for the existing subsea tunnels using the waterproof and drainage design method of "blocking water and limiting drainage", only the water blocking effect of the secondary lining is emphasized or structural safety is emphasized to cause unacceptable drainage costs, or operating expenses are emphasized resulting in that the structure bears an excessive water load and is dangerous. That is to say, the "blocking water and limiting drainage" method of the existing subsea tunnels lacks an objective theoretical basis, and the waterproof and drainage system can only be designed by artificial experience; thus, the waterproof and drainage systems of the subsea tunnels cannot be reasonably designed, leading to problems such as poor waterproof and drainage effect and low safety of tunnel construction.

SUMMARY

An objective of the present invention is to provide a design method and system for an active control type waterproof and drainage system of a subsea tunnel, to solve problems of an existing subsea tunnel such as poor waterproof and drainage effect and low safety of tunnel construction.
To achieve the above objective, the present invention provides the following technical solutions.
A design method for an active control type waterproof and drainage system of a subsea tunnel includes:

acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, wherein the engineering parameter of the subsea tunnel includes a variation range of a seepage field caused by excavation, a permeability coefficient of an original rock, a distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels;
determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel;
determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, to obtain a first determining result;
acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures, if the first determining result indicates that the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, wherein the waterproof and drainage measures include a reinforcing ring waterproof and drainage measure, a primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel include a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads include a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure; and
determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.

Optionally, the determination of an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel specifically includes:
determining the original seepage capacity of the tunnel surrounding rock according to the formula $Q$ $_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
wherein Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
Optionally, the calculating water loads borne by the plurality of different waterproof and drainage measures specifically includes:

determining the first water load borne by the reinforcing ring waterproof and drainage measure by the formula $p$ $_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
determining the second water load borne by the primary support waterproof and drainage measure by the formula $p$ $_{2} = γ_{w} h_{1} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
and
determining the third water load borne by the secondary lining waterproof and drainage measure by the formula $p$ $_{3} = γ_{w} h_{2} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}}),$
wherein p ₁ is the first water load; p ₂ is the second water load; p ₃ is the third water load; h _g is a water head borne by the reinforcing ring waterproof and drainage measure; h ₁ is a water head borne by the primary support waterproof and drainage measure; h ₂ is a water head borne by the secondary lining waterproof and drainage measure; γ_w is seawater density.

Optionally, the determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads specifically includes:

acquiring a first ultimate water load borne by the reinforcing ring waterproof and drainage measure, a second ultimate water load borne by the primary support waterproof and drainage measure, and a third ultimate water load borne by the secondary lining waterproof and drainage measure;
determining whether the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel, to obtain a second determining result;
determining whether the second water load is smaller than the second ultimate water load to obtain a third determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel;
determining whether the third water load is smaller than the third ultimate water load to obtain a fourth determining result, if the third determining result indicates that the second water load is smaller than the second ultimate water load;
determining to use the primary support waterproof and drainage measure as the active control type waterproof and drainage system, if the fourth determining result indicates that the third water load is smaller than the third ultimate water load;
determining whether the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel to obtain a fifth determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is not greater than the allowable drainage capacity of the subsea tunnel; and
determining to use the secondary lining waterproof and drainage measure as the active control type waterproof and drainage system, if the fifth determining result indicates that the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel.

A design system for an active control type waterproof and drainage system of a subsea tunnel includes:

a parameter acquisition module, for acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, wherein the engineering parameter of the subsea tunnel includes a variation range of a seepage field caused by excavation, a permeability coefficient of an original rock, a distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels;
a tunnel surrounding rock original seepage capacity determining module, for determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel;
a first determining module, for determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, to obtain a first determining result;
a tunnel structural seepage capacity and water load determining module, for acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures, if the first determining result indicates that the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, wherein the waterproof and drainage measures include a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel include a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads include a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure; and
an active control type waterproof and drainage system design module, for determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.

Optionally, the tunnel surrounding rock original seepage capacity determining module specifically includes:
a tunnel surrounding rock original seepage capacity determining unit, for determining the original seepage capacity of the tunnel surrounding rock according to the formula $Q$ $_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
wherein Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
Optionally, the tunnel structural seepage capacity and water load determining module specifically includes:

a first water load determining unit, for determining the first water load borne by the reinforcing ring waterproof and drainage measure by the formula $p$ $_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
a second water load determining unit, for determining the second water load borne by the primary support waterproof and drainage measure by the formula $p$ $_{2} = γ_{w} h_{1} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
and
a third water load determining unit, for determining the third water load borne by the secondary lining waterproof and drainage measure by the formula $p$ $_{3} = γ_{w} h_{2} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}}),$
wherein p ₁ is the first water load; p ₂ is the second water load; p ₃ is the third water load; h_g is a water head borne by the reinforcing ring waterproof and drainage measure; h ₁ is a water head borne by the primary support waterproof and drainage measure; h ₂ is a water head borne by the secondary lining waterproof and drainage measure; γ_w is seawater density.

Optionally, the active control type waterproof and drainage system design module specifically includes:

an ultimate water load acquisition unit, for acquiring a first ultimate water load borne by the reinforcing ring waterproof and drainage measure, a second ultimate water load borne by the primary support waterproof and drainage measure, and a third ultimate water load borne by the secondary lining waterproof and drainage measure;
a second determining unit, for determining whether the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel, to obtain a second determining result;
a third determining unit, for determining whether the second water load is smaller than the second ultimate water load to obtain a third determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel;
a fourth determining unit, for determining whether the third water load is smaller than the third ultimate water load to obtain a fourth determining result, if the third determining result indicates that the second water load is smaller than the second ultimate water load;
a first active control type waterproof and drainage system design unit, for determining to use the primary support waterproof and drainage measure as an active control type waterproof and drainage system, if the fourth determining result indicates that the third water load is smaller than the third ultimate water load;
a fifth determining unit, for determining whether the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel to obtain a fifth determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is not greater than the allowable drainage capacity of the subsea tunnel; and
a second active control type waterproof and drainage system design unit, for determining to use the secondary lining waterproof and drainage measure as an active control type waterproof and drainage system, if the fifth determining result indicates that the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel.

According to specific embodiments provided in the present invention, the present invention discloses the following technical effects. The present invention provides a design method and system for an active control type waterproof and drainage system of a subsea tunnel, to determine the active control type waterproof and drainage system of the subsea tunnel based on structural seepage capacities and water loads of the subsea tunnel, design the waterproof and drainage system of the subsea tunnel with inherent objective factors, realize quantitative and rational design of the waterproof and drainage system of the subsea tunnel, and determine corresponding water blocking schemes according to different surrounding rock conditions, thereby reducing the subjectivity of the waterproof and drainage design of the subsea tunnel and improving the scientificity thereof, and at the same time, avoiding waste, and eliminating safety hazards in tunnel construction due to unreasonable design.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show merely some embodiments of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

FIG. 1 is a flowchart of a design method for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention;
FIG. 2 is a comparative diagram of water blocking effects of waterproof and drainage measures provided by the present invention;
FIG. 3 is a flowchart a collaborative optimization design method for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention; and
FIG. 4 is a structural diagram a design system for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention.

DETAILED DESCRIPTION

The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
An objective of the present invention is to provide a design method and system for an active control type waterproof and drainage system of a subsea tunnel, which can improve a waterproof and drainage effect of the subsea tunnel and safety of subsea tunnel construction.
To make the foregoing objective, features, and advantages of the present invention clearer and more comprehensible, the following describes the present invention in more detail with reference to accompanying drawings and specific embodiments.
FIG. 1 is a flowchart of a design method for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention. As shown in FIG. 1, the design method for an active control type waterproof and drainage system of a subsea tunnel includes the following steps.
Step 101: acquire an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, where the engineering parameter of the subsea tunnel includes a variation range of a seepage field caused by excavation, a permeability coefficient of an original rock, a distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels.
Step 102: determine an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel.
Step 103: determine whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel; if yes, go to step 104; if not, go to step 106.
Step 104: acquire structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculate water loads borne by the plurality of different waterproof and drainage measures, where the waterproof and drainage measures include a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel include a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads include a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure.
Step 105: determine the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.
Step 106: determine the current waterproof and drainage measure of the subsea tunnel as the active control type waterproof and drainage system.
Based on the foregoing design method for an active control type waterproof and drainage system of a subsea tunnel, the main technical solutions of the present invention can be divided into the following aspects.

(1) Surrounding rock impermeability prediction. Firstly, predict the original seepage capacity Q1 of the tunnel surrounding rock by a theoretical formula $Q$ $_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
based on the permeability and fracture connectivity of the tunnel surrounding rock; then, determine a drainage capacity control standard [Q4] of the subsea tunnel, according to the difficulty of water blocking, combined with relevant engineering experience; and finally, compare the two; if Q1 < [Q4], determine that the drainage system is sufficient to drain off the water seeped into the tunnel without any additional water blocking measure; if Q1 > [Q₄], determine that the seepage capacity is too large to drain off all water, and it is necessary to carry out "blocking water and limiting drainage"; at the same time, further predict the water load; if the water load is small and the surrounding rock has good impermeability, block the water by the primary support only to meet the requirement; and if the original seepage capacity is large or the water load exceeds the bearing capacity of the primary support, combine the reinforcing ring and the primary support to block the water.
(2) Primary support optimization design. Firstly, with the help of an engineering analogy method and related specifications, preliminarily determine an primary support scheme for the tunnel, and analyze the sensitivity of each parameter by the formula herein to obtain an optimal solution set of primary support parameters, where (the primary support parameters include primary support thickness and permeability coefficient), and based on this, calculate a basic seepage capacity Q₂; if Q₂ > [Q₄], determine that the secondary lining needs to exert a certain water blocking effect; at the same time, respectively analyze ultimate water loads [p₂] and [p₃] of the primary support and the secondary lining, predict actual water loads thereof, and respectively check the support structures; if p₃ < [p₃] and p₂ < [p₂], determine that the selected primary support parameters are reasonable, otherwise determine that the support scheme needs to be adjusted and then checked again until an obtained optimal solution set satisfies: Q₂ < [Q₄] and p₂ < [p₂], or p₃ < [p₃] and p₂ < [p₂] when Q₂ > [Q₄], which indicates that the primary support parameters are reasonable when being satisfied.
(3) Collaborative design of water blocking system. Evaluate a collaborative effect by the indexes of structural seepage capacities and water loads; firstly, with the help of relevant engineering experience and specifications, preliminarily formulate water blocking schemes, and calculate the structural seepage capacity Q₃ of the support scheme and water loads of all water blocking components; similarly, if Q₃ > [Q₄], determine that the secondary lining does not meet safety requirements and the scheme is regarded as an ineffective scheme, finally eliminate a water blocking scheme that does not meet the requirements and structurally fails, compare the support performance utilization ratios of effective schemes, and select a support scheme with the best water blocking effect and the largest overall support performance utilization ratio.
(4) Safety design of secondary lining. Due to the corrosive nature of seawater, the support structures of the tunnel will degrade to some extent under a long-term effect, and considering the most unfavorable situation in the operation process that when the drainage system is completely blocked, the structural seepage capacity cannot be effectively drained off, the secondary lining needs to exert a certain water blocking effect and bear a corresponding additional water load. Therefore, according to the long-term safety requirements of the subsea tunnel, the factor of safety of the support structure system is determined, and the water load to be borne by the secondary lining under the most unfavorable conditions in the long-term operation is predicted, to determine the impermeability grade, strength and stiffness requirements of the secondary lining, and accordingly obtain an optimal support scheme for the secondary lining.

In a practical application, the design method for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention is as follows.

(1) Surrounding rock impermeability prediction. The length of a subsea tunnel is about 6.05 km, including about 4.2 km of the length of a sea area section. To construct the sea area part, there are four deep weathered channels (troughs) with a width of 50-160 m in the subsea structure. The intense weathered channel section in the sea area is typically an unfavorable geological section, with extremely poor surrounding rock conditions, and collapse and water inrush accidents are prone to occur during construction. The excavation width of an unsupported hole of the tunnel is about 17 m, the height is about 12.5 m, and the maximum sectional area of excavation is about 170 m². The original seepage capacity of a surrounding rock is: $Q_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}} = \frac{2 π \cdot 5 \times 10^{- 6} \times 60.5}{\ln 60.5 - \ln 6.5} \times 24 \times 3600 = 73.6 m^{3} (m \cdot d)$
where Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
Taking into account the factors such as the difficulty of water blocking and the risk of water inrush in the weathered channel section, and referring to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels, a drainage capacity control standard of the deep weathered channel section of the subsea tunnel is determined as [Q ₄] = 2.5m³/(m·d), and it can be seen that Q ₁ > [Q ₄]; as the surrounding rock has poor impermeability and an primary support cannot meet the seepage capacity requirement of the tunnel, a reinforcing ring must be combined with the primary support to block the water.
(2) Collaborative design of water blocking system. Six water blocking system schemes are preliminarily determined by an engineering analogy method. Table 1 is a comparative table of parameters of different waterproof and drainage measures. As shown in Table 1, the concrete grade of the primary support is C25, and the permeability coefficient thereof is determined by impermeability grade.

Table 1

Waterproof and drainage measure	Water blocking parameters of reinforcing ring		Water blocking parameters of primary support
Waterproof and drainage measure	Thickness t _g/m	Relative permeability coefficient n _g	Thickness t ₁/cm	Relative permeability coefficient n ₁
1	5	100	40	500
2	5	200	30	250
3	6	50	40	500
4	6	100	30	500
5	7	100	40	250
6	7	50	30	500

The seepage capacity of the tunnel is expressed by: $Q = \frac{2 {πk}_{s} (h_{0} - h_{3})}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}}$
where k_g is the impermeability coefficient of the reinforcing ring; k ₁ is the impermeability coefficient of the primary support; k ₂ is the impermeability coefficient of the secondary lining; r_g is the external radius of the reinforcing ring after grouting; r ₁ is the external radius of the primary support; r ₂ is the external radius of the secondary lining.
Water loads borne by the reinforcing ring, the primary support and the secondary lining are respectively: $p_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}})$
$p_{2} = γ_{w} h_{1} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}})$
$p_{3} = γ_{w} h_{2} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}})$
where p ₁ , p ₂ and p ₃ are water loads respectively borne by a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure and a secondary lining waterproof and drainage measure; h_g , h ₁ and h ₂ are water heads borne by the reinforcing ring waterproof and drainage measure, the primary support waterproof and drainage measure and the secondary lining waterproof and drainage measure; γ_w is seawater density.
The structural seepage capacities of the tunnel and water loads in all the schemes are calculated respectively according to the formulas (2) to (5). FIG. 2 is a comparative diagram of water blocking effects of the waterproof and drainage measures provided by the present invention. It can be seen that for Scheme 3 and Scheme 6, the calculated structural water seepage capacity Q ₃ > [Q ₄], which means that the secondary lining needs to passively bear a certain water load, but it is not considered unsafe when Q ₃ > [Q ₄]; as the surrounding rock conditions in the F1 weathered channel section are extremely poor, and the design value of the load on the surrounding rock of the secondary lining is large, the water load should be reduced as much as possible in the structural design; for safety considerations, the secondary lining should not bear the water load, so the foregoing two schemes are eliminated.
For other schemes, the water loads of the reinforcing ring are basically equal and are about 0.6 MPa. Since the water load p₂ of the primary support is smaller than p₁, the safety of the reinforcing ring can be evaluated approximately by the following formula: $f_{g} = 2 \frac{p_{1} r_{g}^{2}}{r_{g}^{} - r_{0}^{2}} - σ_{ci} s^{a}$
where σ_ci is uniaxial compressive strength of an intact rock; s and a are material parameters, having the following expressions: ${\begin{matrix} s = \exp (\frac{GSI - 100}{9 - 3 D}) \\ a = \frac{1}{2} + \frac{1}{6} [\exp (- \frac{GSI}{15}) - \exp (- \frac{20}{3})] \end{matrix}$
The uniaxial compressive strength of a reinforced rock mass is $σ_{c} = σ_{c i} s^{a}$
It can be seen that the strength of the reinforced rock mass only needs to reach 1.76 MPa to meet requirements, and measured data shows that after composite grouting in the F1 deep weathered channel construction of the subsea tunnel, the strength of the reinforced rock mass reaches 15 MPa or more, thus the safety of the reinforcing ring is guaranteed, with a large margin. Therefore, the collaborative degree of the water blocking system mainly depends on the water load borne by the primary support. It is obvious that the primary support bears the minimum water load of merely 0.02 MPa in Scheme 2, and calculating by Formula (9) shows that the safety of the primary support meets requirements. $f_{1} = 2 \frac{p_{2} r_{1}^{2}}{r_{1}^{2} - r_{0}^{2}} - 2 c \frac{\cos φ}{1 - \sin φ}$
in the formula, c is a cohesive force of primary support members; ϕ is an internal friction angle. ${\begin{matrix} c = \frac{\sqrt{σ_{tp} σ_{cp}}}{2} \\ φ = \arctan \frac{σ_{cp} - σ_{tp}}{2 \sqrt{σ_{tp} σ_{cp}}} \end{matrix}$
where σ _cp is uniaxial compressive strength of primary support member materials; σ_tp is uniaxial tensile strength of primary support member materials.
In addition, selecting a water blocking scheme should consider the difficulty of its implementation. According to field experience, a water blocking scheme is easy to implement when the permeability coefficient of the reinforcing ring reaches 2.5×10^-6 m/s, and the primary support can achieve the permeability coefficient of 2 × 10^-6 m/s by selecting shotcrete with impermeability grade of P4. Based on the foregoing analysis, it can be determined that Scheme 2 is the optimal water blocking scheme for the weathered channel section.

(3) Safety design of secondary lining

As a safe reserve for water blocking of the tunnel, the secondary lining structure should also have a certain water blocking capacity to meet the long-term durability requirement of the tunnel. Therefore, the secondary lining structure will also bear a certain water load in response to the deterioration of the surrounding rock and the primary support structure during the long-term operation.
The secondary lining is regarded as a thick-surroundinged cylinder, and its ultimate bearing capacity can be expressed as: $p_{\max} = \frac{σ_{cs}}{2} [1 - \frac{r_{0}^{2}}{{(r_{0} + t_{2})}^{2}}]$
where σ _cs is uniaxial compressive strength of concrete; t ₂ is thickness of the secondary lining.
The factor of safety (FS) of the secondary lining or safe reserve can be expressed as: $FS = \frac{p_{\max}}{p}$
A large number of engineering practices have shown that with the passage of time, the seepage capacity has a tendency to gradually decrease; considering the most unfavorable situation in the service period of the tunnel that the secondary lining bears 0.61 MPa of full water head and load when the drainage system is completely blocked, the commonly used concrete grade of the secondary lining is C30, and the thickness of the secondary lining may not be less than 30cm by Formula (11); considering the evolution law of stratum loads, the thickness of the secondary lining is 40 cm. Based on the foregoing analysis, the following suggestions are made for the water blocking system scheme of the weathered channel section of the subsea tunnel, as shown in Table 2, a table of suggestions for the water blocking system scheme of the weathered channel section of the subsea tunnel provided by the present invention. Table 2

Reinforcing ring Primary support Secondary lining

Thickness tg/m Relative permeability coefficient ng Thickness t1/cm Relative permeability coefficient n1 Thickness t2/cm

5 200 30 250 40
Based on the application of the design method for an active control type waterproof and drainage system provided by the present invention, FIG. 3 is a flowchart a collaborative optimization design method for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention.
FIG. 4 is a structural diagram of a design system for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention. As shown in FIG. 4, the design system for an active control type waterproof and drainage system of a subsea tunnel includes a parameter acquisition module 401, a tunnel surrounding rock original seepage capacity determining module 402, a first determining module 403, a tunnel structural seepage capacity and water load determining module 404, and an active control type waterproof and drainage system design module 405.
The parameter acquisition module 401 is configured for acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, where the engineering parameter of the subsea tunnel includes the variation range of a seepage field caused by excavation, the permeability coefficient of an original rock, the distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels.
The tunnel surrounding rock original seepage capacity determining module 402 is configured for determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel.
The tunnel surrounding rock original seepage capacity determining module 402 specifically includes: a tunnel surrounding rock original seepage capacity determining unit, for determining the original seepage capacity of the tunnel surrounding rock by the formula $Q$ $_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
where Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
The first determining module 403 is configured for determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, to obtain a first determining result.
The tunnel structural seepage capacity and water load determining module 404 is configured for acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures, if the first determining result indicates that the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, where the waterproof and drainage measures include a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel include a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads include a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure.
The tunnel structural seepage capacity and water load determining module 404 specifically includes:

a first water load determining unit, for determining the first water load borne by the reinforcing ring waterproof and drainage measure by the formula $p$ $_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
a second water load determining unit, for determining the second water load borne by the primary support waterproof and drainage measure by the formula $p$ $_{2} = γ_{w} h_{1} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}});$
and
a third water load determining unit, for determining the third water load borne by the secondary lining waterproof and drainage measure by the formula $p$ $_{3} = γ_{w} h_{2} = γ_{w} (h) (_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r} + \ln \frac{R_{0}}{r_{g}}}),$
where p ₁ is the first water load; p ₂ is the second water load; p ₃ is the third water load; h_g is a water head borne by the reinforcing ring waterproof and drainage measure; h ₁ is a water head borne by the primary support waterproof and drainage measure; h ₂ is a water head borne by the secondary lining waterproof and drainage measure; γ_w is seawater density.

The active control type waterproof and drainage system design module 405 is configured for determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.
The active control type waterproof and drainage system design module 405 specifically includes:

an ultimate water load acquisition unit, for acquiring a first ultimate water load borne by the reinforcing ring waterproof and drainage measure, a second ultimate water load borne by the primary support waterproof and drainage measure, and a third ultimate water load borne by the secondary lining waterproof and drainage measure;
a second determining unit, for determining whether the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel, to obtain a second determining result;
a third determining unit, for determining whether the second water load is smaller than the second ultimate water load to obtain a third determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel;
a fourth determining unit, for determining whether the third water load is smaller than the third ultimate water load to obtain a fourth determining result, if the third determining result indicates that the second water load is smaller than the second ultimate water load;
a first active control type waterproof and drainage system design unit, for determining to use the primary support waterproof and drainage measure as the active control type waterproof and drainage system, if the fourth determining result indicates that the third water load is smaller than the third ultimate water load;
a fifth determining unit, for determining whether the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel to obtain a fifth determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is not greater than the allowable drainage capacity of the subsea tunnel; and
a second active control type waterproof and drainage system design unit, for determining to use the secondary lining waterproof and drainage measure as the active control type waterproof and drainage system, if the fifth determining result indicates that the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel.

The design method and system for an active control type waterproof and drainage system of a subsea tunnel provided by the present invention creatively propose a waterproof and drainage design scheme of blocking water by using the reinforcing ring and the primary support for the subsea tunnel, give the calculation method of the seepage capacity and the water load, which is easy to be understood and accepted by a designer, has strong operability, and makes the calculation results better in conformance with the actual situation by considering the impermeable differences of different surrounding rock conditions, and at the same time, can evaluate the collaborative effect of the waterproof and drainage system of the subsea tunnel, fully exert the impermeability of the support structures, and improve the scientificity and economy of the waterproof and drainage design of the subsea tunnel.
Each embodiment of the present specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts between the embodiments may refer to each other. For a system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and reference can be made to the method description.
Several examples are used for illustration of the principles and implementation methods of the present invention. The description of the embodiments is used to help illustrate the method and its core principles of the present invention. In addition, those skilled in the art can make various modifications in terms of specific embodiments and scope of application in accordance with the teachings of the present invention. In conclusion, the content of this specification shall not be construed as a limitation to the invention.

Claims

A design method for an active control type waterproof and drainage system of a subsea tunnel, comprising:
acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, wherein the engineering parameter of the subsea tunnel comprises a variation range of a seepage field caused by excavation, a permeability coefficient of an original rock, a distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels;

determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel;

determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, to obtain a first determining result;

acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures, if the first determining result indicates that the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, wherein the waterproof and drainage measures comprise a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel comprise a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads comprise a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure; and

determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.
The design method for an active control type waterproof and drainage system of a subsea tunnel according to claim 1, wherein the determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel specifically comprises:
determining the original seepage capacity of the tunnel surrounding rock according to the formula $Q_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
wherein Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
The design method for an active control type waterproof and drainage system of a subsea tunnel according to claim 2, wherein the calculating water loads borne by the plurality of different waterproof and drainage measures specifically comprises:
determining the first water load borne by the reinforcing ring waterproof and drainage measure by the formula $p_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}});$

determining the second water load borne by the primary support waterproof and drainage measure by the formula $p_{2} = γ_{w} h_{1} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}});$
and

determining the third water load borne by the secondary lining waterproof and drainage measure by the formula $p_{3} = γ_{w} h_{2} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}}),$
wherein p ₁ is the first water load; p ₂ is the second water load; p ₃ is the third water load; h_g is a water head borne by the reinforcing ring waterproof and drainage measure; h ₁ is a water head borne by the primary support waterproof and drainage measure; h ₂ is a water head borne by the secondary lining waterproof and drainage measure; γ_w is seawater density.
The design method for an active control type waterproof and drainage system of a subsea tunnel according to claim 3, wherein the determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads specifically comprises:
acquiring a first ultimate water load borne by the reinforcing ring waterproof and drainage measure, a second ultimate water load borne by the primary support waterproof and drainage measure, and a third ultimate water load borne by the secondary lining waterproof and drainage measure;

determining whether the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel, to obtain a second determining result;

determining whether the second water load is smaller than the second ultimate water load to obtain a third determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel;

determining whether the third water load is smaller than the third ultimate water load to obtain a fourth determining result, if the third determining result indicates that the second water load is smaller than the second ultimate water load;

determining to use the primary support waterproof and drainage measure as the active control type waterproof and drainage system, if the fourth determining result indicates that the third water load is smaller than the third ultimate water load;

determining whether the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel to obtain a fifth determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is not greater than the allowable drainage capacity of the subsea tunnel; and

determining to use the secondary lining waterproof and drainage measure as the active control type waterproof and drainage system, if the fifth determining result indicates that the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel.
A design system for an active control type waterproof and drainage system of a subsea tunnel, comprising:
a parameter acquisition module, for acquiring an engineering parameter of the subsea tunnel and an allowable drainage capacity of the subsea tunnel, wherein the engineering parameter of the subsea tunnel comprises a variation range of a seepage field caused by excavation, a permeability coefficient of an original rock, a distance from the center of the tunnel to the sea level, and an equivalent excavation radius; the allowable drainage capacity of the subsea tunnel is determined with reference to the allowable drainage capacity specifications of Japan's Seikan Tunnel and Norwegian subsea tunnels;

a tunnel surrounding rock original seepage capacity determining module, for determining an original seepage capacity of a tunnel surrounding rock according to the engineering parameter of the subsea tunnel;

a first determining module, for determining whether the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, to obtain a first determining result;

a tunnel structural seepage capacity and water load determining module, for acquiring structural seepage capacities of the tunnel corresponding to a plurality of different waterproof and drainage measures, and calculating water loads borne by the plurality of different waterproof and drainage measures, if the first determining result indicates that the original seepage capacity of the tunnel surrounding rock is greater than the allowable drainage capacity of the subsea tunnel, wherein the waterproof and drainage measures comprise a reinforcing ring waterproof and drainage measure, an primary support waterproof and drainage measure, and a secondary lining waterproof and drainage measure; the structural seepage capacities of the tunnel comprise a first structural seepage capacity of the tunnel corresponding to the reinforcing ring waterproof and drainage measure, a second structural seepage capacity of the tunnel corresponding to the primary support waterproof and drainage measure, and a third structural seepage capacity of the tunnel corresponding to the secondary lining waterproof and drainage measure; the water loads comprise a first water load borne by the reinforcing ring waterproof and drainage measure, a second water load borne by the primary support waterproof and drainage measure, and a third water load borne by the secondary lining waterproof and drainage measure; and

an active control type waterproof and drainage system design module, for determining the active control type waterproof and drainage system according to the structural seepage capacities of the tunnel and the water loads.
The design system for an active control type waterproof and drainage system of a subsea tunnel according to claim 5, wherein the tunnel surrounding rock original seepage capacity determining module specifically comprises:
a tunnel surrounding rock original seepage capacity determining unit, for determining the original seepage capacity of the tunnel surrounding rock according to the formula $Q_{1} = \frac{2 {πk}_{s} (h_{0} - h_{3})}{{\ln R}_{0} - {\ln r}_{0}},$
wherein Q ₁ is the original seepage capacity of the tunnel surrounding rock; R ₀ is the variation range of a seepage field caused by excavation; k_s is the permeability coefficient of an original rock; h ₀ is the distance from the center of the tunnel to the sea level; r ₀ is an equivalent excavation radius; h ₃ is a water head in the tunnel.
The design system for an active control type waterproof and drainage system of a subsea tunnel according to claim 6, wherein the tunnel structural seepage capacity and water load determining module specifically comprises:
a first water load determining unit, for determining the first water load borne by the reinforcing ring waterproof and drainage measure by the formula $p_{1} = γ_{w} h_{g} = γ_{w} (h_{0} - \frac{h_{0} - h_{3}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}});$

a second water load determining unit, for determining the second water load borne by the primary support waterproof and drainage measure by the formula $p_{2} = γ_{w} h_{1} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) (\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}})}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}});$
and

a third water load determining unit, for determining the third water load borne by the secondary lining waterproof and drainage measure by the formula $p_{3} = γ_{w} h_{2} = γ_{w} (h_{3} + \frac{(h_{0} - h_{3}) \frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}}}{\frac{k_{s}}{k_{2}} \ln \frac{r_{2}}{r_{0}} + \frac{k_{s}}{k_{1}} \ln \frac{r_{1}}{r_{2}} + \frac{k_{s}}{k_{g}} \ln \frac{r_{g}}{r_{1}} + \ln \frac{R_{0}}{r_{g}}}),$
wherein p ₁ is the first water load; p ₂ is the second water load; p ₃ is the third water load; h_g is a water head borne by the reinforcing ring waterproof and drainage measure; h ₁ is a water head borne by the primary support waterproof and drainage measure; h ₂ is a water head borne by the secondary lining waterproof and drainage measure; γ_w is seawater density.
The design system for an active control type waterproof and drainage system of a subsea tunnel according to claim 7, wherein the active control type waterproof and drainage system design module specifically comprises:
an ultimate water load acquisition unit, for acquiring a first ultimate water load borne by the reinforcing ring waterproof and drainage measure, a second ultimate water load borne by the primary support waterproof and drainage measure, and a third ultimate water load borne by the secondary lining waterproof and drainage measure;

a second determining unit, for determining whether the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel, to obtain a second determining result;

a third determining unit, for determining whether the second water load is smaller than the second ultimate water load to obtain a third determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel;

a fourth determining unit, for determining whether the third water load is smaller than the third ultimate water load to obtain a fourth determining result, if the third determining result indicates that the second water load is smaller than the second ultimate water load;

a first active control type waterproof and drainage system design unit, for determining to use the primary support waterproof and drainage measure as an optimal waterproof and drainage measure, if the fourth determining result indicates that the third water load is smaller than the third ultimate water load;

a fifth determining unit, for determining whether the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel to obtain a fifth determining result, if the second determining result indicates that the second structural seepage capacity of the tunnel is not greater than the allowable drainage capacity of the subsea tunnel; and

a second active control type waterproof and drainage system design unit, for determining to use the secondary lining waterproof and drainage measure as an optimal waterproof and drainage measure, if the fifth determining result indicates that the third structural seepage capacity of the tunnel is greater than the allowable drainage capacity of the subsea tunnel.