Soluble Rocks Research Articles

A New Method for Determining the Safety Distance Between Irregular Karst Cave and Circumferential Shield Tunnel

ABSTRACTWhen a shield tunnel passes through a karst area, the water‐filled cave can easily make the surrounding rock metamorphic, resulting in water inrush, ground collapse, and shield machine failure and other engineering hazards. Natural cavities have a significant degree of geometric irregularity due to groundwater alteration and soluble rock erosion. Considering the difficulties in describing the shape of a natural irregular cavity, circular, rectangular, and elliptical geometries have been simplified in most related studies. Based on the upper bound theorem of limit analysis, we established a three‐dimensional failure model including the karst caves located directly above and below the circumferential side of the tunnel. Then, we deduced the corresponding analytical solution of the critical safety distance (CSD). Furthermore, the effects of rock mass parameters, cave parameters, and geometric parameters on the CSD were analyzed. Then we designed the numerical simulation considering the irregular geometry shape at the circumferential side of tunnel using the Fourier descriptors. In addition, we estimated the CSDs for two failure models using the revised dichotomy and failure criterion. The findings demonstrated a quantifiable association between CSD and Fourier descriptors of irregular cave shape, resulting in the development of a CSD prediction model. These test results can provide a theoretical foundation and direction for predicting water inrush caused by the constrained irregular cave.

Realistic Simulation of Dissolution Process on Rock Surface

Hydraulic dissolution, driven by carbon dioxide-rich precipitation and runoff, leads to the gradual breakdown and removal of soluble rock materials, creating unique surface and subsurface features. Dissolution is a complex process that is related to numerous factors, and the complete simulation of its process is a challenging problem. On the basis of deep investigation of the theories of geology and rock geomorphology, this paper puts forward a method for simulating the dissolution phenomenon on a rock surface. Around the movement of water, this method carries out dissolution calculations, including processes such as droplet dissolution, water flow, dissolution, deposition, and evaporation. It also considers the lateral dissolution effect of centrifugal force when water flows through bends, achieving a comprehensive simulation of the dissolution process. This method can realistically simulate various typical karst landforms such as karst pits, karst ditches, and stone forests, with interactive simulation efficiency.

Optimizing the heat extraction performance in the Qingfeng Karst geothermal reservoir

Faults are typically associated with hydrothermal reservoirs and may control the heat extraction of geothermal reservoirs. However, in Karst geothermal reservoirs, the dissolution of soluble rocks results in pronounced spatial porosity and permeability anisotropy (PPA), potentially weakening the dominant role of faults. The question arises: which plays a dominant role, PPA or faults? Should geothermal exploitation strategies be adjusted under the interaction of both factors? In this study, we proposed a coupled Thermal-Hydraulic-Geothermal Wellbore (THG) numerical simulation model to streamline the integration of non-isothermal flow and heat transfer processes within a 3D wellbore. Utilizing this model, we analyzed the influence of faults compared to PPA and assessed the geothermal well doublet's heat extraction performance, including thermal breakthrough time, temperature losses along the wellbore wall, and recovery factor (Rg). There are specific geothermal reservoir development conditions leading to the latest thermal breakthrough time and the maximum Rg. The results of contribution rates highlight the influence of injection rate in determining Rg. It is crucial to note that thermal breakthrough time does not necessarily increase with injection temperatures. A more suitable definition for thermal breakthrough time in the Karst geothermal reservoir has also been identified. This study provides an essential reference value for the efficient development of similar Karst geothermal reservoirs.

Coping with Sinkholes: A Systematic Literature Review

Sinkholes have frequently occurred around soluble rock formations, but they have been indirectly related to imprudent human practices, based on long-standing recognition. The aim of this study was to explore how to improve sinkhole hazard management to decrease the extent of related risks. The main methodology was a systematic literature review that identified and synthesized the relevant information. The proposed analytical framework served as the basis for review criteria, and the scope of literature was mainly restricted to relevant text data. Analytical categories and analytical units were both used in the text synthesis process. Sinkholes were traditionally treated as natural events; however, major stakeholders started to pay attention to them as human-induced events under climate change. These players extensively included international organizations, sinkhole-prone countries (e.g., Venezuela, China, Saudi Arabia, etc.), and sinkhole-resistant countries (e.g., United Arab Emirates, Kenya, Australia, etc.) in this study. A key theme in the literature was that these stakeholders would no longer deal with sinkholes as natural events but as human-induced events, based on potential advantages (i.e., managing manmade sinkholes and implementing emergency operation plans). Similarly, as addressing emergency prevention, public awareness, technological application, social challenges, education, and training, the key tenet of study would be further achieved in terms of managerial implications. The results of this study suggested that human activities would act as negative factors in sinkhole occurrence more directly than were indicated previously. Hence, the understanding of sinkhole hazard management would be quite deepened via social environment, while policy makers were to proactively manage the issue with the sincere cooperation of local residents.

Experimental Study of Sinkhole Propagation Induced by a Leaking Pipe Using Fibre Bragg Grating Sensors.

Sinkhole formation caused by leaking pipes in karst soluble rocks is a significant concern, leading to infrastructure damage and safety risks. In this paper, an experiment was conducted to investigate sinkhole formation in dense sand induced by a leaking pipe. Fibre Bragg grating (FBG) sensors were used to record the strain. A balloon was gradually deflated within a bed of wet silica sand to create an underground cavity. Eighteen FBG sensors, with a wavelength range between 1550 nm and 1560 nm, were embedded horizontally and vertically in the physical model at different levels to monitor deformation at various locations. A leaking pipe was installed to induce the collapse of the formed arch above the cavity. The strain measurements suggested the following four phases in the sinkhole formation process: (1) cavity formation, (2) progressive weathering and erosion, (3) catastrophic collapse, and (4) subsequent equilibrium conditions. The results showed differences in the strain signatures and distributions between the horizontal and vertical measurements. During the critical phase of the sinkhole collapse, the horizontal measurements primarily showed tension, while the vertical measurements indicated compression. This investigation demonstrates the effectiveness of FBGs as advanced monitoring tools for sinkhole precursor identification. The study also suggests using FBGs in geotechnical monitoring applications to improve the understanding and mitigation of sinkholes and related geohazards.

Flourishing in Darkness: Protist Communities of Water Sites in Shulgan-Tash Cave (Southern Urals, Russia)

Karst caves, formed by the erosion of soluble carbonate rocks, provide unique ecosystems characterized by stable temperatures and high humidity. These conditions support diverse microbial communities, including wall microbial fouling, aquatic biofilms, and planktonic communities. This study discloses the taxonomic diversity of protists in aquatic biotopes of Shulgan-Tash Cave, a culturally significant site and popular tourist destination, by 18S rRNA gene metabarcoding. Our findings reveal the rich protist communities in the cave’s aquatic biotopes, with the highest diversity observed in Blue Lake at the cave entrance. In contrast, Distant Lake in the depth of the cave was inhabited by specific communities of plankton, mats, and pool fingers, which exhibited lower richness and evenness, and were adapted to extreme conditions (cold, darkness, and limited nutrients). High-rank taxa including Opisthokonta, Stramenopiles, and Rhizaria dominated all biotopes, aligning with observations from other subterranean environments. Specific communities of biotopes inside the cave featured distinct dominant taxa: amoeboid stramenopile (Synchromophyceae) and flagellates (Choanoflagellatea and Sandona) in mats; flagellates (Choanoflagellatea, Bicoecaceae, Ancyromonadida) and amoeboid protists (Filasterea) in pool fingers; flagellates (Ochromonadales, Glissomonadida, Synchromophyceae), fungi-like protists (Peronosporomycetes), and fungi (Ustilaginomycotina) in plankton. The specificity of the communities was supported by LEfSe analysis, which revealed enriched or differentially abundant protist taxa in each type of biotope. The predominance of Choanoflagellatea in the communities of cave mats and pool fingers, as well as the predominance of Synchromophyceae in the cave mats, appears to be a unique feature of Shulgan-Tash Cave. The cold-tolerant yeast Malassezia recorded in other caves was present in both plankton and biofilm communities, suggesting its resilience to low temperatures. However, no potentially harmful fungi were detected, positioning this research as a baseline for future monitoring. Our results emphasize the need for ongoing surveillance and conservation efforts to protect the fragile ecosystems of Shulgan-Tash Cave from human-induced disturbances and microbial invasions.

Chemical improvement of soluble rocks: Foundation of Mosul Dam as case study

The dissolution of soluble rocks (gypsum/anhydrite) beneath the Mosul Dam by water seepage has been observed upon the initial impoundment; consequently, several sinkholes have been manifested in the vicinity of the dam site. Traditional grouting has been envisaged as a potential remedy; however this measure has not eradicated the problem. The main purpose of this study is to overcome the solubility of the gypsum/anhydrite rocks using chemical grouts. Rock samples were acquired from the Fatha Formation outcrop and problematic layers of brecciated gypsum situated at varying depths beneath the Mosul Dam. Two commercially available liquid polymers, polyurethane (PU) and a mixture of acrylic and cement (ARC) were used to investigate their sealing performance in halting of the solubility of the rocks (gypsum/anhydrite). To simulate the dissolution phenomenon under the influence of artificial hydraulic pressure of the dam and the water flow in its abutments, two distinct laboratory models were devised. The outcomes from the experimental study on both untreated and treated samples revealed that the acrylic-cement composite (ARC) and polyurethane (PU) are influential polymers in halting the solubility of the gypsum rock samples under both factors of water pressure and high-velocity water flow.

Prevention of Water Seepage Impact on the Soluble Rocks Using Colloidal Silica

Water seepage flow can dissolve soluble minerals that exist in rock formations. With the development of the excavated area due to dissolution, the water seepage velocity (discharge) into the dissolved rock will also increase. Therefore, water seepage and dissolution propagation are two interrelated processes. Mosul Dam foundation has experienced these processes since its construction, resulting in karstification in the reservoir and foundation of the dam. The present seepage-dissolution measure to minimize this phenomenon relies on traditional cementitious grouts. However, this measure has not been able to address the issue effectively. Currently, there are a few studies on the chemical remediation of soluble rocks under the influence of high-velocity water flow and water pressure. Therefore, the first part of the current study focuses on the impact of high-velocity water flow and water pressure on the dissolution acceleration of gypsum/anhydrite rocks. In the second part, the waterproof capacity of silica colloidal and its impact on the solubility reduction of the rocks is evaluated. Two distinct laboratory models were designed to simulate rock dissolution in the dam abutments and under the dam. Two sets of experiments were conducted on untreated and silica-treated samples. The experiments were executed on the samples extracted from Fatha Formation outcrop and problematic layers of brecciated gypsum situated at varying depths of the Mosul Dam foundation. The obtained findings reveal that the colloidal silica grout markedly prevents the water seepage impact on the soluble rock and that it can be very useful as an alternative to cement-based grouts.

Effects of Afforestation Patterns on Soil Nutrient and Microbial Community Diversity in Rocky Desertification Areas

Karst ecosystems are characterized by the dissolution of soluble rocks, displaying distinctive landscape features such as rugged peaks, steep slopes, and deep valleys. Afforestation is an effective approach for improving soil quality in rocky desertification areas because plants have evolved unique adaptations to thrive in such environments. However, the effects of tree species composition and cultivation patterns on the soil quality, microbial diversity, stability, and functions in rocky desertification areas remain unclear. In this work, four study plots including three types of forests—pure Pinus massoniana plantations, Toona sinensis plantations, mixed coniferous and broadleaf plantations (Pinus massoniana–Betula luminifera forests), and unforested area as the control—were established in a karst desertification area in the Hunan province of China. Soil properties including soil bulk density, soil organic carbon, total nitrogen, total phosphate, soil ammonium nitrogen, nitrate, available phosphate, soil pH, and soil microbial diversity were investigated in the study area. The results showed that the forests significantly increased the soil organic carbon, total nitrogen, and ammonium nitrogen compared to the unforested area. The microbial diversity indicators in mixed forests were significantly higher than those in the Pinus massoniana forests. The dominant bacteria phyla included Proteobacteria, Acidobacteria, and Actinobacteria, while fungi species such as Ascomycota and Basidiomycota were identified in all study plots. In addition, the AVD index evaluation revealed that the mixed forests enhanced the stability of the soil microbial communities compared to the monoculture plantations and unforested plots in rocky desertification areas. The research results indicated that, among the various forest types, the mixed forest was the most effective choice for afforestation in terms of improving the soil quality by changing the soil’s physiological properties in rocky desertification areas. Our study provided guidance and insights for afforestation technology and the optimal allocation of different tree species in the cultivation and management of plantation forests in rocky desertification regions.

Thematic mapping for sediment cascade analysis in small mountain catchments – The case of the Buscagna valley (Lepontine Alps)

The multi-scalarity of mountain systems primarily relates to their complex structural settings, which lead to the fragmentation of geological and geomorphological units. This may have strong implications for the hydrogeomorphological evolution of watersheds and the related sediment cascades. In the framework of this research, we selected the small Buscagna mountain catchment in the Lepontine Alps (Northwestern Italy), where the northern slope comprises very resistant gneissic rocks, while soluble rocks (i.e., marble) – in some case intensely foliated (i.e., calcschist) –crop out along the southern slope. The diversification of geomorphological processes and landforms (i.e., geomorphodiversity) is highly evident, and various techniques are applied to create thematic maps of geomorphological features (landforms; processes; erosion/deposition/deformation), sediment connectivity, and source/store/sink distribution in the Buscagna catchment. The obtained thematic maps were integrated and compared to depict the influence of bedrock features on geomorphological evolution. The geomorphological maps focussed on landforms and processes reveal that glacial and gravity-related processes and permafrost distribution are deeply influenced by the topographic and lithological dichotomy of the catchment. Permafrost distribution is again uneven in the basin, and its degradation allows relevant sediment sources to be delivered downstream. Lastly, debris flows represent the primary connectivity triggers between areas such as the hanging glacial basin slopes and the valley bottom (i.e., erosion/deposition/deformation and index of connectivity maps). What emerges is the importance of integrating and comparing different thematic maps for a correct interpretation of the past and present dynamics influencing the evolution of complex, albeit small, mountain catchments.

Detection for severe caves and sinkholes in non-clastic rock type using GPR technique

ABSTRACT This study examines the application of Ground Penetrating Radar (GPR) to the detection of severe caverns and sinkholes in non-clastic rock formations. Due to the presence of vertically sloping bedrock, cavities, and sinkholes, geotechnical engineers face significant challenges when designing and constructing foundations in karstic formations such as limestone. The territory under investigation is located close to the Giza limestone plateau, the northern side of which has experienced severe stability issues. The ground-penetrating radar (GPR) method was used to identify the presence and extent of exposed caves and caverns in the studied region. The research area’s geological and geomorphological background is explored, including the creation of primary and secondary caves, as well as solution caves generated by the breakdown of soluble rocks like limestone. Data collecting, processing, and interpretation procedures used in the GPR survey are described. GPR survey findings revealed the existence of a severe cave and many minor sinkholes in the studied region. GPR has shown to be a useful and efficient tool for determining geometric karst features in the subsurface, helping to a better evaluation of the dangers associated with this geological environment.

Underground Geodiversity of Italian Show Caves: an Overview

About a fifth of the Italian territory is characterised by the presence of soluble rocks, consisting mainly of limestone and dolostone but also of marble and evaporite rocks (gypsum). More than 50,000 natural caves are currently known in this country, a number that is constantly increasing thanks to speleological exploration. Less than 1% of these caves are equipped for visits, and only 64 can be defined as real show (tourist) caves. In the latter, it is necessary to buy an entrance ticket, visits take place only accompanied by a guide, and the underground trail is equipped with paths, walkways and, generally, lighting systems. The Italian show caves expose a great geodiversity and biodiversity, often accompanied by a considerable historical and/or archaeological interest. The underground geodiversity of Italian show caves is related to the variety of lithologies characterising this territory and to the geomorphological and geodynamic processes that have been active during different geological periods. Important scientific research has taken place in many of these caves, and several of these fragile environments are monitored continuously to verify their environmental conditions.

Degradation Characteristics and Mechanism of Black Sandy Dolomite with Fluid Added in a Mechanical Test

Sandy dolomite, being a soluble rock, is prone to dissolution and erosion caused by groundwater, leading to the formation of underground caves and fractures. This may result in geological disasters such as ground subsidence and collapse. In this paper, the changes and mechanical properties of black sandy dolomite after hydrochemistry are studied. A semi-immersion test with different concentrations of iron sulfate solution was carried out to simulate the water-rock interaction in different water environments. After that, scanning electron microscope (SEM) results could reflect the dissolution and pore development of rock by the effect of water-rock interaction from the microscopic. Water-rock interaction enlarges cracks in rocks and dissolves pyrite, carbonate minerals, and other components, reducing the cementation between particles. The change in the mechanical properties of black sandy dolomite under water-rock chemical interaction was revealed by uniaxial compression test. The mechanical properties of the samples exhibit varying degrees of deterioration, with strain increased ranging from 4.96 to 29.58%. The brittleness index modified (BIM) values for each sample ranged from 5.20 to 6.20%, all of which are larger than 4.70% in the natural state.

Characteristics and Connectivity Analysis of Hidden Karst in Jurong Pumped Storage Power Station Area, China

Based on the hidden karst exposed in Jurong Pumped Storage Power Station, combined with the field exploration data, the temporal and spatial development characteristics of hidden karst in the power station area are analyzed using the methods of specific solubility and specific corrosion, water chemical composition analysis, borehole television imaging, tracer test, and water pressure test. The results show that the karst development in the study area can be divided into three periods: pre-Cretaceous, Pleistocene, and modern karst. Karst development is controlled by soluble rock, non-soluble rock, and their combination, and the development direction is basically consistent with the fault strike. Karst caves are mainly distributed below the elevation of 100 m, with different shapes and scales and randomness. Non-soluble rocks and impure carbonate rocks are widely distributed in the study area, and surface karst is not developed. The underground karst caves are filled with red clay, and the rate of groundwater circulation is slow. The existence of geological bodies such as rock veins causes the groundwater levels to have obvious double-layer characteristics, which results in weak connectivity between karst caves. Although the karst in the power station area has a certain hydraulic connection with the surface water outside the area, the hydraulic connection of karst in the power station area is generally weak. The research results provide a scientific basis for the anti-seepage measures of underground powerhouses.

Application and comparison of very low frequency electromagnetic and electrical resistivity techniques to investigate a Karstic Region: A case study of EL Hajeb Municipality, Morocco

Geophysical methods are widely used to determine subsurface karst structures' depth because of their risks. However, their qualitative or quantitative interpretations involve a degree of uncertainty. Consequently, several methods are used to improve the credibility of drawn conclusions. In this study, we used two well-known geophysical methods, namely Very Low Frequency Electromagnetic (VLF-EM) and electrical resistivity methods, to characterize the observed or suspected sinkholes in an area of the municipality of El-Hajeb, Morocco, where no previous research had been conducted. This built-up zone is characterized by soluble carbonate rocks and sinkholes, which qualifies it as a high-risk area. We also compared four interpretation methods to estimate the depth of anomalies from VLF-EM data: Derived Euler Deconvolution (DED) and Extended Euler Deconvolution (EED) which, to authors' knowledge, have not been applied before, Karous-Hjelt (K-H) pseudosections, and Classic Euler Deconvolution (CED). Electrical resistivity data were used to confirm the VLF-EM results. The findings indicated that some conductive anomalies, manifested by decreased real component and apparent resistivity, are in good agreement with shallow sinkholes and depressions observed in the study area. In addition, other conductive anomalies indicate hidden sinkholes. The estimated depths of an observed sinkhole from K-H pseudosections, CED, DED, and by electrical resistivity tomography are comparable. The finding of this study revealed the effectiveness of the used geophysical methods to identify karst features. It also demonstrated the efficacy of the VLF-EM data processing tools, particularly CED and DED, to estimate the depth of these features, with the exception of the EED, which unexpectedly provided large depth values.

A joint geophysical approach to tune an integrated sinkhole monitoring method in evaporitic environments

AbstractSeveral methodologies allow for the detection and mapping of existing sinkholes in order to asses and manage the associated hazards and risks. These phenomena, linked to the presence of soluble rocks, are well known globally as they can cause severe damage to man‐made structures. In this paper, we propose an integrated method applied to a test‐site area in NE Italy where, on May 11 2017, a failure shaped like a sinkhole, suddenly occurred along a main regional road, which then had to be closed to traffic in part as a result of a landslide developing on the slope just upstream from the surface depression which had already formed. The slope was reprofiled, a paved barrier was placed at the toe of the slope, and the road itself was finally repaired and restored. In the test site, a detailed morphological and geological survey was performed, as well as several integrated multi‐scale geophysical investigations, both in correspondence to the sinkhole location and in surrounding areas where other depressions were found. Results confirm the absence of large cavities down to the maximum investigated depth and highlighted a complex geological situation with abrupt lateral variations, a straight correlation between different geomorphological and geological elements, and the role of water paths. Geophysical investigations were found to be a useful tool to monitor the future evolution of the identified phenomena and to prevent further collapses and disasters along roads.

Scaling laws for ablation waves formed by ice sublimation and rock dissolution: applications to the Earth, Mars and Pluto

Ablation waves involve solid substrate such as ice or soluble rocks. Ablation by sublimation or dissolution under turbulent winds or liquid flows may lead to the development of transverse linear bedforms (ablation waves) on volatile or soluble susbtrates. In glaciology, geomorphology, karstology and planetology, these ablation waves may provide relevant morphological markers to constrain the flows that control their formation. For that purpose, we describe a unified model, that couples mass transfers and turbulent flow dynamics and takes into account the relationship between the viscosity of the fluid and the diffusivity of the ablated material, for both sublimation and dissolution waves. From the stability analysis of the model, we derive three scaling laws that relate the wavelength, the migration velocity and the growth time of the waves to the physical characteristics (pressure, temperature, friction velocity, viscous length, ablation rate) of their environment through coefficients obtained numerically. The laws are validated on terrestrial examples and laboratory experiments of sublimation and dissolution waves. Then, these laws are plotted in specific charts for dissolution waves in liquid water, for sublimation waves in N2-rich atmospheres (e.g., Earth, Titan, Pluto) and in CO2-rich atmospheres (e.g., Mars, Venus). They are applied to rock dissolution on the walls of a limestone cave (Saint-Marcel d’Ardèche, France), to H2O ice sublimation on the North Polar Cap (Mars) and to CH4 ice sublimation in Sputnik Planitia (Pluto), to demonstrate how they can be used (1) either to derive physical conditions on planetary surfaces from observed geometric characteristics of ablation waves (2) or, conversely, to predict geometric characteristics of ablation waves from measured or inferred physical conditions on planetary surfaces. The migration of sublimation waves on regions of the Martian North Polar Cap and sublimation waves candidates on Pluto are discussed.

Fosforo disponible de tres fuentes en el suelo y su efecto sobre la biomasa y desarrollo radical del maíz

Phosphorus deficiency in the country is very common, to overcome the problem high soluble phosphates are applied, the use a less soluble acidulated phosphate rock with sulfuric acid (RFA) is one economical alternative. The partial substitution of sulfuric acid by ammonium thiosulfate in the acidulation process (R30T) has proven feasible. The objective of this study was to prove the effect of these P sources on the maize behavior. Two soils were used a neutral and acidic one. Four doses of P treatments were used: 0, 70, 140 and 210 mg.kg-1, in a glasshouse experiment. 35 days after planting plants were harvest and soil and root samples were taken for phosphorus analysis and determination of dry matter, root length (LR) and root volume (VR). Partial substitution of sulfuric acid by ammonium thiosulfate does not affect the quality of the acidulated rock. A close relationship between biomass and P concentration in the corn tops with residual soil P, LR and VR increased with the first increase of soil P, successive increments of P produced a decrease in roots size. The LR and VR relationship with P uptake and biomass was not the same in the two soils, in the acidic soil there was a higher dependence on P uptake than in the neutral soil.

Study on the crystallisation formation mechanism and breakage of tunnel drainage system in dolomite area

AbstractDolomite is a soluble salt rock, and in dolomite locations, tunnel drainage systems are frequently clogged by crystallisation, resulting in tunnel leaks. This research starts with a field survey to investigate the environmental conditions that influence crystal formation and sample collection. Afterward, the crystals underwent examination using EDS, scanning electron microscopy (SEM) and XRD, which enabled the analysis of crystals' elemental composition, matter composition and microstructure. Finally, a measure for crystal removal using ultrasound is proposed. The feasibility of ultrasonic crystal removal was verified by the indoor model experiment. The results show that the crystals contain mainly metallic elements such as Ca, Mg and Al. The main component of the crystals is CaCO3. The crystals also contain small amounts of Mg (OH)2, Al (OH)2 and CaAl2(SO4)3(OH)2‐26H2O. As the ultrasonic frequency increases, the de‐crystallisation effect becomes more pronounced. At ultrasonic frequencies greater than 50 kHz, the growth in crystal break‐up efficiency tends to level off. Therefore, the ultrasonic frequency based on this parameter will be used to remove the crystals.

Water Inrush Mechanism and Treatment Measures in Huali Highway Banyanzi Tunnel—A Case Study

In the process of tunnel construction, the water inrush disaster is one of the main engineering geological disasters. In karst strata, different types of water-bearing structures or karst water bodies develop and occur in the soluble rock layer, and tunnel excavation easily forms new drainage channels, resulting in water inrush in the tunnel. Based on the project of the Huali Highway Banyanzi Tunnel, this paper studies the water inrush characteristics, water inrush mechanism, and treatment measures of the karst tunnel. According to the basic data, combined with field investigation, data monitoring, geological radar detection, tracer test, and numerical simulation, the characteristics and hydrogeological conditions of the tunnel water surge were investigated and analyzed. In addition, the mechanism of tunnel water surge was further summarized. Moreover, the tunnel water-gushing management measures are optimized and verified based on the tunnel water spraying mechanism.