Soil Tunnel Research Articles

Study on Stability of Excavation Surface of Shield Tunnel in Clay Layer

If an excavation surface becomes unstable, it will cause damage such as soil collapse or surface uplift. Through field investigations and tests, the stability of the shield tunnel excavation surface and its influencing factors are studied in this paper. Equations for solving the limit support pressure of the excavation surface of the overlying multilayer soil tunnel and for the safety factor of the excavation surface are deduced. The single reduction method and the double reduction method are respectively used to solve the safety factor of the excavation face under the basic working conditions, and the numerical simulation method of the safety factor of the excavation face is clarified. Based on FLAC3D numerical simulation software, the ultimate support pressure and safety factor were used as the evaluation criteria for the stability of the excavation face to analyze the response of objective factors such as internal friction angle and cohesion, as well as engineering factors such as hole diameter to the stability of the excavation face. The greater the internal friction angle and cohesion, the smaller the hole diameter, the more stable the excavation surface, and the internal friction angle has the greatest impact on the stability of the excavation surface.

Adaptive mesh refinement using Octree for finite cell simulation and its application for tunneling in saturated soils

AbstractDuring simulations of complex engineering processes that include the domain evolution in time and space, it is often impossible to predict which regions should have finer numerical discretization in advance. In such cases, adaptive mesh refinement (AMR) can be used to achieve higher accuracy of the solution for as little computational cost as possible. This is achieved by locally refining the mesh only in areas of interest, which leads to a considerable saving in computational and storage requirements in comparison to global refinement [1]. Further, AMR reduces the effort needed by the user to tailor a high‐quality mesh for the specific problem at hand.Tree‐based refinement methods use a recursive encoding scheme and a hierarchical refinement of non‐overlapping elements, making them efficient and simple. These methods also ensure that the quality of the elements will not degrade and provide fine scale adaptivity [2]. Moreover, these methods are highly scalable with low overhead (see, e.g., [3]). The P4est library manages the AMR topology and uses tree‐based refinement to create a forest of octrees. It is also designed to work in parallel and scale well to a high number of processor cores. Hanging nodes resulting from bisection refinement are handled using constraints with the master‐slave elimination method. Data storage and data transfer between meshes are also handled.The effectiveness of the proposed framework is demonstrated by large scale simulations of the tunneling process in two‐phase soft soils [4]. A structured grid is used together with AMR to create meshes for arbitrary tunnel alignments which substantially reduces preprocessing time. The soil domain is modeled using the Finite Cell method (FCM) with a non‐boundary conforming mesh while the other tunneling components are modeled using a boundary fitted mesh.

Seismic performance of soil–tunnel–building systems in stiff soils

In order to study seismic soil–tunnel–building interaction in stiff soils, a metro station currently under construction, located near by a 5-story masonry building, was selected as a test site for seismic instrumentation. The site is in Mexico City, in the so-called hill zone, where very cemented sandy silt and silty sands can be found. An arrangement of five accelerometers were deployed, to assess free-field, near-field, and building seismic response. This article presents the results gathered from the seismic instrumentation after recording five low- to high-magnitude earthquakes (i.e. ranging from 4.8 to 7.7 Mw) from both interface and intraplate events. The results clearly indicate that even in low- to medium-magnitude events, the presence of the tunnel leads to peak ground acceleration (PGA) amplification both in the horizontal and vertical components, ground motion incoherence, and spectral accelerations (Sa) amplification at high frequencies. Although Sa amplification is more important for intraplate and interface low- to medium-magnitude events, frequency content modification occurs regardless of the earthquake magnitude. These facts must be accounted for when designing low- to medium-rise structures underlaid or nearby underground infrastructure such as tunnels in highly populated urban areas.

Experimental and Numerical Investigation on Soft Soil Tunnels Under Impact Loading Condition

Experimental and Numerical Investigation on Soft Soil Tunnels Under Impact Loading Condition

Predicting of Seismic Performance on Tunnel in Weak Soil

Main seismic situations have appeared that the tunnels in weak soil may be suffer large seismic damage. Suitable modeling can have great significance for predicting and estimating their seismic acting. This paper examines the effect of the tunneling process and the seismic effect on the tunnel model and the surrounding soil on it. The data of this research is from Almafraq overhead intersection project in the Diyala government, the soil consists of clay and sand layers in which the tunnel is set up. The data obtained from field and laboratory investigations of soil layers and the analysis of the tunneling model by three-dimensional finite element analyses using PLAXIS 3D (V 20), the Mohr-Coulomb (MC) model is employed to demonstrate the behavior of soil-structure interaction in a soil tunnel. Plastic counting was used to act as an elastic-plastic distortion. Three sections are chosen in the vertical direction to experiment with the tunnel's impact and seismic effect on nearby soils. From proceeding FE analysis, the results of calculation by math measurement appeared to main variations in stresses that happen in soils zones nearby the tunnel edges and below the tunnel essentially affect nearness to soils. The increasing pressure becomes smaller as much as you went away horizontally from the tunnel and start to decrease for lengths more than 15m from the tunnel edge's, so it was observed that the most probable safe distance (2D) from the tunnel, which D represents the diameter of the tunnel, this for tunneling. Also, the upper zone of the tunnel considers safer at 58% because it is far from the influence of the earthquake and its soil is clay, while the critical zone locates in contact with the tunnel. Furthermore, it was noted that the amount of settlement of the soil is so little in a phase of tunnelling compared to the dynamic rate of 86%.

Intelligent Analysis of Construction Costs of Shield Tunneling in Complex Geological Conditions by Machine Learning Method

The estimation of construction costs for shield tunneling projects is typically based on a standard quota, which fails to consider the variation of geological parameters and often results in significant differences in unit cost. To address this issue, we propose a novel model based on a random forest machine learning procedure for analyzing the construction cost of shield tunnelling in complex geological conditions. We focus specifically on the unit consumption of grease, grouting, labor, water, and electricity. Using a dataset of geotechnical parameters and consumption quantities from a shield tunneling project, we employ KNN and correlation analysis to reduce the input dataset dimension from 17 to 6 for improved model accuracy and efficiency. Our proposed approach is applied to a shield tunneling project, with results showing that the compressive strength of geomaterial is the most influential parameter for grease, labor, water, and electricity, while it is the second most influential for grouting quantity. Based on these findings, we calculate the unit consumption and cost of the tunnelling project, which we classify into three geological categories: soil, soft rock, and hard rock. Comparing our results to the standard quota value, it is found that the unit cost of shield tunneling in soil is slightly lower (6%), while that in soft rock is very close to the standard value. However, the cost in the hard rock region is significantly greater (38%), which cannot be ignored in project budgeting. Ultimately, our results support the use of compressive strength as a classification index for shield tunneling in complex geological conditions, representing a valuable contribution to the field of tunneling cost prediction.

Blowout analysis of shallow elliptical tunnel faces in frictional-cohesive soils

Because of high space utilization, elliptical cross-section sometimes is adopted in the design of urban pedestrian underpasses, underground common ditches and subway tunnels. Nevertheless, theoretical models on the blowout failure analysis of shallow elliptical tunnel faces are quite rare. Within the framework of the kinematical approach of limit analysis, deterministic and probabilistic blowout analyses of a shallow elliptical tunnel in frictional-cohesive soils are performed in this study. With the help of the spatial discretization technique, an improved blowout failure mechanism for shallow elliptical tunnel faces is generated. Compared with previous analytical or semi-analytical ones, such an improved failure mechanism allows variable frictional angles of soils to be readily accounted for. The critical blowout face pressure is determined based on the work rate balance equation and a hybrid global optimization algorism. The deterministic model is validated by numerical simulations, existing experimental results and theoretical solutions, in which the effect of the geometrical parameter of elliptical tunnel faces and the less computational cost over numerical simulations are emphasized. Deterministic parametric analyses are conducted to investigate the influences of several significant parameters in the form of charts. Probabilistic blowout analyses of tunnel faces excavated in spatially rotated anisotropy varying soils are then conducted via a combination of the subset simulation, the random field theory and the Markov Chain Monte Carlo method, and the influence of characteristic parameters of the random field are examined. In the end, a case study is presented to demonstrate the practical use of the proposed model.

Semi-analytical solutions of three-dimensional ground movements due to shallow tunnelling

This paper presents the semi-analytical solutions to predict the three-dimensional ground movements of shallowly buried tunnels in clayey and sandy soils based on the virtual image technique. Both the ground nonuniform convergence and the tunnel ovalization are taken into account in the proposed method. The accuracy of the proposed method is verified by comparing with the results from field monitoring, numerical simulation and existing solutions. The results indicate that the transverse surface settlements mainly occur within H/tan(45° + φ/2) + R from the tunnel axis on both sides of the tunnel, and the variations of the longitudinal surface settlements are mainly produced within ± 2H from the tunnel face. The internal friction angle, Poisson’s ratio, cover depth and tunnel diameter have significant effects on the surface and subsurface movements according to the parametric analysis. The proposed method can serve as a practical tool in the preliminary design of tunnels and provide a theoretical basis for ensuring the construction safety of actual engineering.

Stochastic Dynamic Response and Long-Term Settlement Performance of Superstructure–Underground Tunnel–Soil Systems Subjected to Subway-Traffic Excitation

The vibration impact force from the long-term operation of a subway affects the comfort of the residents living above the superstructure and the long-term settlement deformation of the tunnel foundation. A method for evaluating the dynamic responses of superstructure–tunnel systems is important, especially because of the randomness of vibration impact force. The coupling effect of the randomness of train-vibration excitation and the nonlinearity of the geotechnical properties that are subjected to dynamic action leads to challenges in the evaluation of the performance of superstructure–underground tunnel–soil systems under train vibration. In this study, a stochastic dynamic model of subway vibration-load excitation was established; then, the time histories of samples with rich probability characteristics in the same set system were generated. According to the nonlinear dynamic finite element analysis, several nonlinear dynamic responses of the deterministic superstructure–tunnel soil-foundation system were obtained. Finally, the probabilistic performance evolution of the superstructure–tunnel soil-foundation system was obtained by integrating the first-passage and probability density evolution theories, and the long-term deformation performance of the tunnel foundation was evaluated using time-varying reliability. This study presents a novel probabilistic method and a more objective performance index for the dynamic performance assessment of superstructure–underground tunnel–soil systems that are subjected to subway-traffic excitation.

Study on Seismic Response and Vibration Reduction of Shield Tunnel Lining in Coastal Areas

The construction of subway tunnels in the coastal section is affected by special soil quality, with complex construction conditions of unstable soil and vulnerability to groundwater corrosion. The design difficulty of subway tunnels is greatly increased, and the safety performance in the event of an earthquake is greatly reduced. To study the changes in shield tunnel lining structure under earthquake and propose damping measures, ANSYS software is used to conduct tunnel soil numerical simulation. Firstly, static analysis and modal analysis are carried out, and it is found that the maximum displacement deformation occurs at 3.8 cm of the arch crown, and the maximum stress occurs at 2.6 × 107 Pa of the left and right wall corners, 8 easily deformed points are obtained at the same time. Input EI_Centro EW forward 19 s seismic wave is used to analyze the displacement, acceleration and stress vibration characteristics of tunnel lining. The upper part of the lining is more vulnerable to earthquake, and the right arch waist is subject to the maximum stress, reaching 1.37 × 10−4 Pa, the maximum displacement deformation point is 3.65 × 10−10 m at the right wall. To reduce the impact of earthquakes on tunnel lining, the damping scheme of adding an isolation layer is adopted. Using foam concrete isolation material can reduce the stress of the arch waist by 74.6%, and rubber isolation material can reduce the stress by 80%. In consideration of groundwater corrosion and subsequent engineering construction, it is recommended to use foam concrete as the material for the isolation layer. This study can provide a theoretical basis for the design of metro tunnels in offshore areas.

Characterization of Mechanical Behavior of Ultra-Small Clearance Tunnel Construction in Upper Soil and Lower Rock Composite Strata

It is hard to grasp the deformation law of the surrounding rock and the force characteristics of the support structure during the construction of ultra-small clearance tunnels in upper soil and lower rock composite strata. Based on the ultra-small clearance tunnel in Li Shuping, Tongxin Expressway, Guizhou, this paper adopted a combination of numerical simulation and field monitoring to analyze the influence of different burial depths and soil-rock interface positions on the deformation of the surrounding rock and the internal forces of the support structure of the ultra-small clearance tunnel. The conclusions are: (1) the monitoring data show that the stress in the steel frame of the leading tunnel increases first by the influence of proximity construction, and then decreases and reaches a stable value after the secondary lining is applied, and the stress at the arch waist of the soft soil layer furtherest from the side of the middle rock column is greater than that in the rock layer on the side of the middle rock column; (2) the position of the soil-rock interface has a significant influence on the initial support force of the first tunnel, and the bending moment of the structure increases with the downward movement of the soil-rock interface and the increase in the burial depth; (3) the influence of the soil-rock interface position on the initial support moment of the first tunnel is greater than the influence of proximity construction, a point to which attention should be paid during construction; and (4) when the soil-rock interface is located below the foot of the arch, the deformation of the surrounding rock of the following tunnel will be larger than that of the first tunnel. The results can provide a reference for the design and construction of ultra-small clearance tunnels in upper soil and lower rock composite soft strata and soil strata.

A Study on the Formation Mechanism and Calculation Method of Surrounding Rock Pressure in Shallow-buried Loess Tunnel Considering the Influence of Vertical Joints

Vertical joints have significant effects on the stability of shallow-buried loess tunnel. Due to the presence of vertical joints distributed widely in loess, the formation mechanisms of surrounding rock pressure on shallow-buried loess tunnel and its computational method are far different from those in other types of soil tunnel. In this study, the distribution characteristics of surrounding rock pressure in shallow-buried loess tunnel were investigated, and discrete element software 3DEC was used to analyze the formation mechanism and development process of surrounding rock pressure in loess tunnel under the influence of joints. We correlated the stratum deformation characteristic with the frictional force caused by the mutual dislocation between joints, and revised the semi-empirical method (Chinese Code methods) in China. The results show that the measured data of radial surrounding rock pressure of shallow-buried loess tunnel are generally between 0–600 kPa, and 80% in the range of 0–200 kPa. The surrounding rock pressure increases with the burial depth, while the distribution of lateral pressure coefficient is relatively discrete. The existence of loess vertical joints (LVJs) aggravates the uneven distribution of the vertical pressure above the tunnel, and the reduction of the lateral earth pressure coefficient at rest under the influence of joints leads to an increase in pressure near the arch shoulder, these two constitute the essence of the joints action on the surrounding rock pressure. The surrounding rock pressure of the shallow-buried loess tunnel reaches the peak stress at about 0.5D from the tunnel face (D is the tunnel span), which is about 1.04–1.32 times of the initial stress. After the excavation of the upper step, the stress of the tunnel crown monitoring point decreased to about 60% of the initial stress. Compared with ignoring the influence of joints, the time of reaching the peak stress at the arch shoulder monitoring point is earlier, and the final stress release degree is smaller. The comparison of the analytical results (proposed method) with the numerical results and the field data exhibits good agreement, proving the proposed method's correctness.

Analysis of existing railway deformation caused by double shield tunnel construction in soil–rock composite stratum

Subway tunnel construction often crosses existing railways, and the soil loss caused by shield construction will inevitably lead to deformation of the surrounding strata and uneven settlement of the adjacent railway tracks, but there are few studies on the existing railway deformation caused by double shield construction in soil–rock composite strata. In this paper, based on the field monitoring data, the deformation analysis of the railway under-crossed by double shield tunnel in soil–rock​ composite stratum was carried out, and the influence law of hard-layer ratio, tunnel burial depth and railway roadbed reinforcement on the railway track deformation was revealed by numerical simulation. Results show that the track settlement mainly occurred in the middle and late stages of the shield crossing the railway. The track settlement showed an obvious trend of decreasing with the increase of hard-layer ratio or tunnel buried depth. The roadbed reinforcement can significantly reduce the settlement of the railway track, the smaller the hard-layer ratio, the better the roadbed reinforcement effect.

Evolution of tunnel uplift and deformation induced by an upper and collinear excavation: A case study from Shenzhen metro

This paper presented a case study in Shenzhen metro where the evolution of the tunnel uplift and deformation was investigated based on the field observation. The deformation of tunnel, diagram wall and ground surface were carefully measured over 400 days. The tunnels had been significantly uplifted by 34 mm, while less convergence deformation was observed in each section. For the long excavation collinear to the underlying tunnel in Shenzhen granite residual soil, the superposition unloading of the other adjacent upper and collinear excavation activities has a more significant impact on the tunnel uplift compared to the excavation of upper section, which lead to more than half of the tunnel uplift amount. In addition, a slight twist deformation was observed in the tunnel section, which need to be focused in the evaluation of tunnel safety because it is a main contribution to the tunnel diseases. The well-document site data and results can provide systematic field data and useful engineering reference for similar projects.

Improved Theoretical Solutions for Estimating the Tunnel Response Induced by Overlying Excavation

As a result of China’s urbanization, it has been a common phenomenon that adjacent deep excavations were constructed near underground structures, which can have a series of detrimental effects on existing tunnels. Thus, it is crucial to assess the tunnel response induced by the overlying excavation, with the aim of maintaining the safety and serviceability of operating tunnels. The shield tunnel is idealized as an infinite beam lying upon a three parameter Kerr-model and the vertical force equilibrium equation of the tunnel element is established. Then, a theoretical solution is derived for capturing the soil–tunnel interaction. To prove the accuracy of the proposed method, the calculation results are compared with field measurements, along with the data of finite element studies. Thereafter, a parametric analysis will be conducted to assess some characteristic factors for tunnel responses caused by overlying excavations, such as tunnel-excavation horizontal distance, tunnel bending stiffness, and the buried depth of the tunnel. The results indicate that the increase in the bending stiffness and the buried depth of tunnel, as well as the tunnel-excavation horizontal distance, will significantly alleviate the tunnel deformation. However, the inner force will be increased when increasing the tunnel bending stiffness.

A frequency-domain formulation for predicting ground-borne vibration induced by underground train on curved track

The vibration caused by underground trains running on a curved track often has a greater impact on residents, buildings, or sensitive instruments than that of a straight track. A formulation including two frequency-domain models for simulating the generation and propagation of train-induced vibrations is presented in this study. Based on an analytical model of a curved track subjected to moving forces, an approach to determine the wheel–rail contact forces and excitation forces acting on the roadbed from the measured dynamic response of the rails is developed. Frequency-domain excitation forces are applied to a periodic finite element–infinite element model to predict ground-borne vibration. In this model, the tunnel structure and soils in the near field are modelled as finite elements, whereas infinite elements are used to simulate wave propagation in the far-field soils. An experiment to measure the vibrations on the rail and ground surface during train passages in the Beijing metro was conducted to validate the proposed formulation. It is shown that high computational efficiency and accuracy in this formulation can be expected in the prediction of ground-borne vibration in a curved tunnel–soil system.

Stability evaluation of circular tunnels in cohesive frictional soil under earthquake loading using the modified pseudo-dynamic approach

The peripheral stability of tunnels is maintained by installing support systems in the form of linings. The required resistance of the linings depends on the stresses exerted by the surrounding medium. This study evaluated the support pressure of the lining for circular tunnels in cohesive-frictional soil under earthquake loading by applying the modified pseudo-dynamic approach in the finite element lower bound limit analysis framework. The normal stresses exerted by the surrounding soil vary along the tunnel's periphery, and the tunnel's stability is ensured when the minimum support pressure offered by the tunnel lining is equal to or greater than the maximum normal stress exerted by the soil at the ultimate failure condition. The horizontal and vertical earthquake accelerations, amplitude, and phase of the accelerations were varied with depth by satisfying the stress boundary conditions. The shear strength parameters of soil (cohesion and friction angle), tunnel cover and its diameter, and the parameters owing to an event of an earthquake (acceleration, frequency of primary and shear waves, and the time of shaking) influence the magnitude and location of maximum normal stress along the tunnel's periphery.

How Did Vinh Moc Village, Located near Vietnam DMZ, Protect Their Villagers from United States Air Force Bombardment during the Vietnam War?

The buried village is Vinh Moc where more than 1200 Vietnamese, including soldiers, who lived underground during the Vietnam War (1965 to 1972) were hand dug into red basalt bedrock. The Vinh Moc Village was strategically located on the border of North Vietnam and South Vietnam approximately 14 km north of the DMZ and along the shoreline of the South China Sea. During the Vietnam War, the US Air Force heavily bombed Vinh Moc. The North Vietnamese Army (NVA) had an important military base on nearby Con Co Island. Brave civil volunteers from Vinh Moc would make the 28 km dangerous journey to the island, disguised as fishermen, to deliver supplies to the soldiers stationed there. The people who remained at Vinh Moc dug tunnels into red basalt hills in order to survive this onslaught. The American forces assessed the villagers of Vinh Moc were supplying food and armaments to the NVA garrison on the island of Con Co, which was in turn hindering the American bombers on their way to bomb Hanoi. The US military objective was to force the villagers of Vinh Moc to leave the area. The villagers initially dug the tunnels to a 10 m depth but the American forces designed bombs that burrowed down 10 m before exploding. The soil tunnels were then deepened to 30 m to provide safety for the soldiers and civilians working there during the intense US Air Force bombing. The primary objective of the research study was to determine how the soils and parent material of Vinh Moc Village, protected their villagers from the United States Air Force bombardment during the Vietnam War. In addition, the natural parent material at both the Vinh Moc and Cu Chi were assessed to determine why the tunnels were so resilient. The Cu Chi and Iron Triangle soil tunnels were dug by hand in the Old Alluvium soils and parent material where iron in solution precipitated and became the soil binding material. The Vinh Moc tunnels were hand dug in porous, red basalt (bedrock) hills where the consolidated rock structure itself provided the required binding material. Neither site needed support beams to hold up the ceilings.

Research on the Application of Backwall Grouting in Leakage Treatment of Operating Tunnels

In order to study the application of grouting behind the lining wall in the treatment of leakage of subway tunnel during the operation period, the diffusion effect of grouting behind the wall in dense fill and loose fill was studied by the method of numerical simulation and model test, and the distribution of grouting vein in the process of grouting was analyzed. The results show that the results of numerical simulation and model test are basically the same, mainly as follows: In the dense soil, although the slurry will also expand along the tunnel lining wall, it is mainly jacking in the direction perpendicular to the lining structure, and it is unable to form a large area of enclosed solid behind the lining structure; In the loose soil, with the increase of grouting pressure, the slurry gradually approaches the wall After approaching the wall, it will expand along the wall, and, at the end of grouting, the slurry will be evenly distributed along the back of the tunnel lining structure and form an obvious closed reinforcement. It is concluded that: for the tunnel structure in loose soil, when the measures of grouting behind the wall are adopted to treat the leakage water, the spacing of grouting holes can be appropriately enlarged; for the tunnel in dense soil, the spacing between grouting holes should not be too large. More importantly, the correct grouting scheme design must be considered from the whole reinforced soil, rather than from the effect of a certain point. According to the specific situation and the expansion process of the slurry, the expansion direction of the slurry vein should be considered scientifically, so as to achieve good treatment effect of leakage water.

Saigon River Valley: A Navigation, Trade, Mitigation, Invasion, Liberation, and Unification Pathway

The Saigon River is located in southern Vietnam with headwaters starting in southeastern Cambodia. The river flows southeast for about 225 km to the South China Sea. Most readers of Vietnam’s history know about the American-Vietnam War (1965-1973). However, centuries before that time, Vietnam fought with the Chinese, the Khmers, the Chams and the Mongols. The history of Vietnam begins in the Red River Delta, where farmers first cultivated rice. A millenia of struggle against the Chinese then followed. The Saigon River Valley was the pathway used by the North Vietnamese Army (NVA) to get from the Ho Chi Minh Trail in Cambodia to Saigon during the 1968 Tet Offensive. The NVA dug Cu Chi and Iron Triangle soil tunnels near Cu Chi in the Old Alluvium terrace to hide from American Forces and Air Force bombers. In 1962, the Tan Son Nhut Air Force base on the northern edge of Saigon received the first shipments of Agent Blue, the arsenic based herbicide, used to destroy the rice crop. The most dioxin TCDD and arsenic contaminated site in Vietnam was Bien Hoa Air Force base on the Saigon River just 30 km northeast east of Ho Chi Minh City. The adjacent Bien Hoa City has a population of over 800,000. The Port of Ho Chi Minh City is the most significant river port in Vietnam and Southeast Asia. The river is navigable by ships which draft up to 9 m. Vietnam only became a united country in the 19th century. Its independence was soon affected by French colonialism and then the destructive American intervention in the Vietnam War. The Vietnam War Archive no. 2 in Ho Chi Minh City houses residual correspondence between the Republic of Vietnam (RV) President Diem’s administration and US President Kennedy’s administration related to the Khai Huang program (hamlet strategy). In addition, the archive contains some of the tactical herbicide spray records of the RV military for the Mekong Delta. The primary objective this study is to document the role that the Saigon River Valley played, in modern warfare. The Saigon River Valley was used as a navigation, trade, invasion, liberation and unification pathway. The Vietnamese people have survived centuries of stormy, troubled times and their power of character has served them well.