Patent Number: 
Section: claims

1. A construction layout for underground caverns in a nuclear island powerhouse of an underground nuclear power plant, the construction layout comprising:a) two primary caverns accommodating nuclear reactor powerhouses;b) two assemblies of combined caverns;c) two electric powerhouse caverns;d) two pressure relief caverns;e) a first primary traffic tunnel;f) a second primary traffic tunnel;g) a third primary traffic tunnel;h) a top adit system;i) a ground adit system;j) secondary traffic tunnels; andk) a side traffic tunnel;wherein:a connecting line of centers of cross-sections of the two primary caverns at a horizontal plane is perpendicular to a longitudinal direction of a mountain, wherein the horizontal plane is parallel to a ground surface and the longitudinal direction of the mountain;each cavern of the two assemblies of combined caverns and the two electric powerhouse caverns comprises a rectangular cross-section having a longitudinal axis at the horizontal plane;each assembly of combined caverns and each electric powerhouse cavern are disposed at two sides of one primary cavern, respectively; the two assemblies of combined caverns are in end-to-end connection and the longitudinal axis of each cavern of the two assemblies of combined caverns and the two electric powerhouse caverns is in parallel to the connecting line of the centers of cross-sections of the two primary caverns; each pressure relief cavern is disposed between one assembly of combined caverns and a corresponding electric powerhouse cavern;outer sides of caverns in the two assemblies of combined caverns are connected to a side traffic tunnel disposed outside the two assemblies of combined caverns via the secondary traffic tunnels; two ends of the side traffic tunnel are connected to the first primary traffic tunnel and the third primary traffic tunnel arranged along the longitudinal direction of the mountain;the two assemblies of combined caverns are disposed between the first primary traffic tunnel and the third primary traffic tunnel; the second primary traffic tunnel is arranged along the longitudinal direction of the mountain between the first primary traffic tunnel and the third primary traffic tunnel and is connected to a middle part of the two assemblies of combined caverns;each of the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel communicates with the ground surface;the two primary caverns, the two assemblies of combined caverns, the two electric powerhouse caverns and the two pressure relief caverns form a cavern group of the nuclear island powerhouse of the underground nuclear power plant;the top adit system communicates with the ground surface;skewbacks or endwalls of top arches of caverns of the cavern group communicate with the ground surface via the top adit system;bottoms of sidewalls of caverns of the cavern group communicate with the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel via the ground adit system; and bottoms of sidewalls of caverns of the cavern group communicate with the ground surface via the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel;the top adit system is adapted for excavating caverns;the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel are adapted for discharging excavated materials; andthe top adit system is disposed at a higher elevation with respect to the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel. 2. The layout of claim 1, wherein:the top adit system comprises: a first primary adit, a first top adit, a second top adit, a second primary adit, a third primary adit, a fourth primary adit, two third top adits, a fourth top adit, and a fifth top adit;the first primary adit, the second primary adit, the third primary adit, and the fourth primary adit are arranged along the longitudinal direction of the mountain and communicate with the ground surface; an elevation of the first primary adit is higher than an elevation of the second primary adit, an elevation of the third primary adit, and an elevation of the fourth primary adit;the first primary adit is connected to skewbacks of arch crowns of the two primary caverns via the first top adit and the second top adit, respectively;the second primary adit and the fourth primary adit are connected to endwalls of arch crowns of two ends of the two assemblies of combined caverns; the third primary adit are connected to a skewback of an arch crown of the middle part of the two assemblies of combined caverns;a middle part of the third primary adit is branched to form the two third top adits connected to endwalls of arch crowns of the two electric powerhouse caverns; the third primary adit is branched to form the fourth top adit connected to a skewback of an arch crown of one of the two pressure relief caverns; the fourth primary adit is branched to form the fifth top adit connected to a skewback of an arch crown of the other of the two pressure relief caverns; andthe fourth top adit is disposed between one of the two third top adits and the two assemblies of combined caverns. 3. The layout of claim 2, wherein each top adit of the top adit system has a longitudinal slope smaller than 9%. 4. The layout of claim 3, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively. 5. The layout of claim 2, wherein:the ground adit system comprises: a first bottom adit, a second bottom adit, a third bottom adit, a fourth bottom adit, a fifth bottom adit, a sixth bottom adit, a seventh bottom adit, an eighth bottom adit, and a ninth bottom adit;a middle section of the first primary traffic tunnel is branched to form the third bottom adit connected to an endwall of one of the two electric powerhouse caverns; a middle section of the second primary traffic tunnel is branched to form the ninth bottom adit connected to an endwall of the other of the two electric powerhouse caverns;the second primary traffic tunnel is connected to a bottom of a sidewall of one of the two primary caverns and a bottom of one of the two pressure relief caverns via the first bottom adit and the fifth bottom adit, respectively;the third primary traffic tunnel is connected to a bottom of a sidewall of the other of the two primary caverns and a bottom of the other of the two pressure relief caverns via the sixth bottom adit and the seventh bottom adit, respectively; andthe first primary traffic tunnel is connected to a bottom of a sidewall of one end of the two assemblies of combined caverns via the second bottom adit; the ninth bottom adit is connected to a bottom of a sidewall of the middle part of the two assemblies of combined caverns via the fourth bottom adit; and the seventh bottom adit is connected to a bottom of a sidewall of the other end of the two assemblies of combined caverns via the eighth bottom adit. 6. The layout of claim 5, wherein each bottom adit of the ground adit system has a longitudinal slope that is smaller than 15%. 7. The layout of claim 6, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively. 8. The layout of claim 5, wherein:each of the two assemblies of combined caverns comprises: a first safe powerhouse cavern, a nuclear fuel powerhouse cavern, a second safe powerhouse cavern, and a nuclear auxiliary powerhouse cavern which are connected in series along a direction perpendicular to the longitudinal direction of the mountain; the nuclear auxiliary powerhouse cavern of one of the two assemblies of combined caverns is connected to the first safe powerhouse cavern of the other of the two assemblies of combined caverns;the second bottom adit is connected to a bottom of a sidewall of the first safe powerhouse cavern disposed at one end of the two assemblies of combined caverns; the fourth bottom adit is connected to a bottom of a sidewall of the nuclear auxiliary powerhouse cavern disposed at the middle part of the two assemblies of combined caverns; the eighth bottom adit is connected to a bottom of a sidewall of the nuclear auxiliary powerhouse cavern disposed at the other end of the two assemblies of combined caverns; andthe second primary adit is connected to an endwall of an arch crown of the first safe powerhouse cavern disposed at one end of the two assemblies of combined caverns; the fourth primary adit is connected to an endwall of an arch crown of the nuclear auxiliary powerhouse cavern disposed at the middle part of the two assemblies of combined caverns; and the third primary adit is connected to an endwall of an arch crown of the nuclear auxiliary powerhouse cavern disposed at the other end of the two assemblies of combined caverns. 9. The layout of claim 8, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively. 10. The layout of claim 5, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively. 11. The layout of claim 2, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively. 12. The layout of claim 1, wherein each of the two primary caverns communicates with a corresponding electric powerhouse cavern via a primary steam channel communicating with the ground surface; and the two primary caverns communicate with the ground surface via corresponding apparatus conveying channels, respectively.